This PDF file contains the front matter associated with SPIE Proceedings Volume 11741, including the Title Page, Copyright information, and Table of Contents.

Defense Advanced Research Projects Agency (DARPA) is developing the technologies to conduct Mosaic Warfare. These are the tools and infrastructure to enable dynamic composition and operation of adaptive, disaggregated systems of systems architectures. When applied to sensing, the tools of Mosaic enable sensing to be conducted as a “team sport” in which we can move away from expensive, complex, exquisite, multi-function monolithic sensors to highly distributed, hyper-specialized sensors in which each individual sensor addresses only a small part of an overall function. This specialization enables deployment of sensors in greater numbers and smaller, cheaper platforms. The presentation will discuss how DARPA is implementing Mosaic, the implications for sensing, and potential dual-use applications in the commercial sector.

This talk will examine the functions of sensing (and sensors) in modern warfare in relation to increasing complexities regarding asymmetric threats, multi-domain operations, and command and control layers and their demands on information processing, situational awareness and networking. New sensors and SWAP-C improvements to existing sensors are increasing numbers and availability of collectors that produce more and more data, while, simultaneously, demand/consumption is also increasing with more users wanting more and more situational awareness. New bottlenecks become evident and drive new requirements needing new solutions for increased data processing, automation and intelligent processing.

Pandemic and budget related impacts to the global supply chain have driven a change in the way we approach partnerships with small businesses and the manpower they provide. This presentation will focus on the importance of cultivating productive and mutually beneficial relationships with suppliers while simultaneously driving economic development in local communities. The talk will also cover the challenge of virtual recruiting, encouraging diversity in the workforce while attracting local talent and the avenues for small business to connect with Lockheed Martin.

Autonomy and AI have made tremendous progress in recent years to the point where operational applications of these technologies can provide decisive advantages. This presentation will discuss the approach recommended to rapidly field autonomy and AI capabilities at scale including the development of a common platform, addressing trust issues, and agile methodology. Examples in sensor exploitation and business processes will be used to demonstrate the operational value of current generation of AI. However, this generation has limitations, and the talk will conclude with future research required to expand the safe, ethical, and effective use of these technologies.

Infrared thermographs (IRTs) have been used for fever screening during infectious disease epidemics. However, their performance is inconsistent in literature, due to wide quality/implementation variations. We overview standards and FDA guidance for IRT performance evaluation, implementation, and regulation policies. Additionally, we present results from a large-scale clinical study of fever-screening IRTs and discuss impact of consensus guidelines and facial measurement location on performance. We found that: high-quality IRTs implemented according to international standards can help to accurately measure temperature; current standards can be improved to further enhance IRT performance. Overall, fever screening is only one element in infectious disease detection.

Introduction to SPIE Defense and Commercial Sensing conference 11741: Infrared Technology and Applications XLVII

In recent years, a worldwide growing demand for Short-Wave Infrared (SWIR) imaging has increased dramatically. The requirement for such imagers span military, space and commercial applications. The ideal SWIR detector realizes low power, small size, and low noise, capable of imaging under a wide range of illuminations from daylight to starlight, with on-die advanced imaging capabilities, such as high dynamic range (HDR) and active imaging. In this paper we present a new 640x512/15μm InGaAs focal plane array (FPA) specifically developed for low noise (LN) applications. The detector temperature is stabilized by a thermoelectrical cooler (TEC) typically at 20 C demonstrating extremely low dark current with excellent imaging under low light level (LLL) conditions. The detector's read out noise was measured to be lower than 15e- with correlated double sampling. We demonstrate the ROICs active imaging applications at sub μs gates and elaborate on the overall electro-optical performance.

Sensors Unlimited Inc. (SUI), a Raytheon Technologies Company, has long been the vanguard of low-noise InGaAs/InP PiN back-side illuminated (BSI) planar-type photodiode technology. In addition to focusing on dark current reduction efforts, SUI has also initiated other photodiode detector array (PDA) improvement efforts to better serve its broad portfolio of sensor technology. In previous years, SUI has presented results related to mesa-structure PDAs for modulation transfer function (MTF) improvement and hybridization capacitance reduction for NEI improvement. An update to these technologies is offered. Additionally, SUI has more recently engaged in more advanced PDA development to better satisfy active imaging applications. Results of these efforts are also presented.

We present gain, dark current and excess noise characteristics of PIN Al_0.85Ga_0.15As_0.56Sb_0.44 (hereafter AlGaAsSb) avalanche photodiodes (APDs) on InP substrates with 1000 nm thick multiplier layers. The AlGaAsSb APDs were grown by molecular beam epitaxy using a digital alloy technique (DA) to avoid phase separation. Current-voltage measurements give a peak gain of ~ 42, a breakdown voltage of – 54.3 V, and a dark current density at a gain of 10 of ~ 145 μA/cm². Excess noise measurements of multiple AlGaAsSb APDs show that k (the ratio of electron and hole impact ionization coefficients) is ~ 0.01. This k-value is comparable to Si, which is widely used for visible and near-infrared APDs. The low dark current density and low excess noise suggest that such thick AlGaAsSb layers are promising multipliers in separate absorption, charge and multiplication (SACM) structures for short-wavelength infrared applications such as optical communication and LIDAR, particularly on a commercial InP platform.

We have fabricated and characterized AlInAsSb- and InPAsSb-absorber nBn infrared detectors with 200 K cutoff wavelengths from 2.55 to 3.25 μm. Minority-carrier lifetimes determined by microwave reflectance measurements were 0.2-1.0 μs in doped n-type absorber materials. Devices having 4 μm thick absorbers exhibited sharp cutoff at wavelengths of 2.9 μm or longer and softer cutoff at shorter wavelengths. Top-illuminated devices with n+ InAs window/contact layers had external quantum efficiencies of 40-50% without anti-reflection coating at 50 mV reverse bias and wavelengths slightly shorter than cutoff. Despite the shallow-etch mesa nBn design, perimeter currents contributed significantly to the 200 K dark current. Dark currents for InPAsSb devices were lower than AlInAsSb devices with similar cutoff wavelengths. For unoptimized InPAsSb devices with 2.55 μm cutoff, 200 K areal and perimeter dark current densities at -0.2 V bias in devices of various sizes were approximately 1x10^-7 A/cm² and 1.4x10^-8 A/cm, respectively.

SiOnyx has demonstrated imaging at light levels below 1 mLux at 60 FPS with a SXGA backside illuminated CMOS image sensor in a compact, low latency camera. Sub mLux imaging is enabled by the combination of enhanced quantum efficiency in the near infrared, backside illumination for 100% fill factor, and state of the art read noise of 1.1 e/pix. The quantum efficiency enhancement is achieved by utilizing SiOnyx’s proprietary nano and microtexturing processing technology in a backside illuminated architecture for high fill factor and enhanced near infrared absorption. The sensors can be configured with Bayer color filters for color imaging below quarter moon.

Colloidal semiconductor quantum dots/graphene van der Waals (vdW) heterojunctions take advantages of the enhanced light-matter interaction and spectral tenability of quantum dots (QDs) and superior charge mobility in graphene, providing a promising alternative for uncooled infrared photodetectors with a gain or external quantum efficiency up to 1010. In these QD/graphene vdW heterostructures, the QD/graphene interface plays a critical role in controlling the optoelectronic process including exciton dissociation, charge injection and transport. Specifically, charge traps at the vdW interface can increase the noise, reduce the responsivity and response speed. This paper highlight our recent progress in engineering the vdW heterojunction interface towards more efficient charge transfer for higher photoresponsivity, D* and response speed. These results illustrate that the importance in vdW heterojunction interface engineering in QD/graphene photodetectors which may provide a promising pathway for low-cost, printable and flexible infrared detectors and imaging systems.

Operating infrared detectors at cryogenic temperatures is vital for attenuating intrinsic thermally-induced noise, thus enabling long working ranges, short integration times, high spatial and temperature resolutions along with other advantages. Unfortunately, the high costs of integrated dewar/detector/cooler assemblies prevent the broad deployment of cooled infrared technology in the price-sensitive and highly competitive commercial market. Uncooled infrared technology, although inferior in performance, is more affordable and, therefore, more ubiquitous. Extending working ranges of uncooled infrared detectors, however, may lead to using expensive and bulky “fast” optics. In a combination with added cost, weight and mechanical complexity of host structures, this may wipe out inherent cost/bulk advantages of uncooled imagers. In some cases, therefore, the cooled infrared imager may be superior in terms of attainable performance, bulk, and system cost.

Traditionally, cryocooler life time and reliability have been a limiting factor for infrared systems, with significant advances having been made over the last two decades. This has culminated in the development, qualification, and production of high-availability cryocoolers, enabling multi-year 24/7 operation of infrared sensors with a vanishingly small failure probability. We will discuss high-availability solutions based on Stirling technology for applications where the intrinsic drawbacks of pulse-tube technology – such as lower efficiency and a high sensitivity to orientation and ambient temperature – restrict the possibilities to use pulse tubes. In addition, we will discuss the applicability of pulse-tube technology to infrared applications.

Development is well underway on a compact cryocooler control electronics (CCCE) module optimized for low power (<20 WAC input) cryocoolers. These electronics are radiation hard to support a wide range of space-borne applications with the expectation that the greatest interest will be for hot mid-wave infrared (HMWIR) space sensors operating around 150K. By focusing on low power coolers and their associated low drive voltages as compared to larger coolers, component selection options open up to include much smaller parts than are typically required for radiation hard cryocooler electronics. The result is a 75% size reduction as compared to the current art in radiation hard cooler electronics. An initial brassboard of the motor drive and telemetry circuits has been successfully built and tested with five different cryocoolers from three different manufacturers, including both Stirling and pulse tube type cryocoolers. An element of the ongoing test program is to better characterize the temperature control firmware to gain understanding, which will lead to more rapid optimization for different cryocoolers and operating points. This paper describes some of the early test results obtained with two small Stirling cryocoolers, an AIM SX035 and a FLIR FL-100.

Improvements made on infrared detectors such as pixel pitch reduction, detector resolution increase, and functions directly integrated at sensor level have impact on the required cryogenic cooling power. Next to that the cryogenic operating temperature of the detector is determined by the used detector technology, required bandwidth and performance and may vary between 60K to 170K. That’s why today, it is important that developed cryogenic coolers are able to address a wide range of cold temperature and cryogenic power, and to be able to predict cryocooler performances at sensor engine level in order to select the best product for a specific IR application. Undeniably the cooler size, weight and consumption are important parameters for the system design but next to that coolers shall be flexible, optimized and efficient to avoid very specific definitions or developments for each type of detector. The paper presents the work made at Thales in order to determine performance models for the legacy products in function of the cold temperature, the dewar characteristics and the ambient temperature. These models are based on a performance mapping. The presentation answers questions such as how to choose a cooler, or how to optimize a cooler in function of the system characteristics. Finally, a new cooler with a larger cooling power as todays series of RM coolers is presented in order to extend the range that can be covered by Thales Rotary products.

Heterogeneous face recognition (HFR) refers to matching face imagery across different domains, such as identifying a thermal probe image given a gallery of visible face images. In this paper, we propose a method for thermal to visible face recognition based on coupled independent component analysis (Coupled ICA). It has been reported that independent component analysis (ICA) of natural scene patches produces a set of visual filters that resemble the receptive fields of simple cells in visual cortex and the projection matrix form a basis of images. Aiming to learn a common latent space for cross-modal images, we propose to learn a separate set of ICA filters which represent the respective imaging system in each domain using a coupled architecture. Coupled ICA assumes the image sources from one domain to be identical to those observed at the other domain. Pairs of image patches in the two domains jointly update the projection matrix in Coupled ICA model. The obtained ICA filters are used to transform images into a domain-independent latent space via patch-wise synthesis. In addition, we add cross-examples into a one-vs-all sparse representation (SR) classification strategy to improve classification performance. Experiments were conducted with the ARL Multi-modal Face Dataset. The results show that the proposed method can fuse the thermal and visible images and outperforms the state-of-the-art methods of cross-modal face recognition.

Visual inspection is the final stage for quality product testing of infrared detectors. Traditional methods for this type of work commonly rely on human visual inspection, which is the ultimate standard for determining the visual quality of the image. However, using human inspection can be problematic because of the statistical variation between observers. Automated methods based on machine learning techniques, and especially Deep Learning, have emerged in recent decades that are able to closely match the visual perception of the human eye, while providing the added benefits of speed and consistency. In the present paper, we propose a hybrid method to classify images acquired from assembled detectors based on the combination of both infrared-adapted image processing techniques and machine learning approaches. The first classifier extracts several features from the infrared image and uses support vector machines (SVM) for classification. The second, a Convolutional Neural Network (CNN), is dedicated to the detection of specific defects, tough to identify with traditional image processing techniques because of their low contrast and is also dedicated to novelty detection. While CNN achieves precise and robust identification of special defects, the first classifier secures the global detection of new defects even if their shape is not clearly identified. The proposed model has proven to be robust and able to accurately classify detectors images, regarding human visual inspection. The approach was developed with the capability to scale-up and evolve in order to take in consideration new products. We also show that using AI presents the double benefit of improving the quality of the products meanwhile reducing human time effort.

The InAs/InSb/GaSb/AlSb family of III-V alloys and superlattice materials offer unique possibilities for band structure engineering, because they can be grown on GaSb or InSb substrates with high quality and satisfactory control of strain, doping and composition. The band profiles and oscillator strengths are also quite predictable, enabling full simulation of detector performance from a basic knowledge of layer and stack thicknesses. In conventional III-V p-n devices, Shockley-Read-Hall (SRH) traps generate a significant flow of thermal carriers in the device depletion region. At SCD, we have overcome this problem by developing XBn and XBp barrier device architectures that suppress these depletion currents, leading to higher operating temperatures or lower dark currents. Our first barrier detector product was launched in 2013 and operates at 150K. It uses a mid-wave infrared (MWIR) XBn device with an InAsSb absorber well matched to the most transparent of the atmospheric windows, at wavelengths between 3 and 4.2μm. However to span the full MWIR and to sense the long-wave infrared (LWIR) spectrum, we have investigated InAs/GaSb type II superlattices (T2SLs), because they offer full tunability. In this work we show that minority carriers in n-type T2SLs are localized and diffuse by variable range hopping, even when the period is short and the valence miniband has a width of 30-40 meV. Unfortunately, this leads to sub-micron diffusion lengths and a low quantum efficiency (QE) of ~20% in a full MWIR XBn device. On the other hand, p-type layers exhibit “metallic” minority carrier transport with much longer diffusion lengths, typically ~7 μm in our LWIR device layers. The successful development of p-type devices has led to our second barrier detector product, which uses an XBp LWIR T2SL and operates at 77K with a cut-off wavelength of 9.5 μm, a focal plane array (FPA) QE of ~50% and background limited performance up to ~90K at F/3. Moreover, the FPA operability is typically above 99.5%, based on stringent production-line criteria. Together with high spatial uniformity and good temporal stability, these barrier detectors are already a realistic alternative to MCT photodiode arrays, and further products operating at other wavelengths will be launched in due course.

During last decade, several Government-funded programs resulted in a groundbreaking new infrared focal plane array (FPA) material that serves as a low cost and more reliable FPA alternative for DoD military systems. These new IR FPAs use the Sb-based III-V semiconductor Type-II Superlattice (T2SL) infrared detector technology with bandgap-engineered device architectures. Follow on programs have accelerated the manufacturability of T2SL FPAs sensitive in single and multiple infrared bands with inherent operability, uniformity, and stability advantages. Today, T2SL materials grown on very-large diameter (up to 6”) gallium antimonide (GaSb) substrates with higher processing yields provide a much lower cost option for very large format staring imagers in mid- and long-wavelength infrared bands. This talk reviews the current state of T2SL FPA technology and discusses remaining challenges for further advancement of this infrared detector technology.

Dual-band infrared photodetectors with a modified pBp design have been demonstrated. The modified pBp structure consisted of a p-type InAs/GaSb superlattice for long-wavelength (LW) detection and a p-type InAs/GaSb/AlSb based superlattice for mid-wavelength (MW) detection, which were separated by a hole barrier consisting of an InAs/AlSb superlattice. Our pBp device showed that dual-band detection was possible by changing the bias polarity of the applied voltage. By using an InAs/GaSb/AlSb based superlattice as an MW absorber for a pBp photodetector, a 100 % cutoff wavelength was blue-shifted from 8 μm to 7 μm compared with a conventional InAs/GaSb superlattice, while maintaining the same 50 % cutoff wavelength of around 6.4 μm. Quantum efficiency per period of the modified MW absorber was comparable with that of a conventional MW absorber. These results indicate that our modified pBp structure is expected to be a promising candidate for dual-band infrared photodetectors.

Due to the demand for increasingly large format focal plane arrays, smaller and smaller pixels are required for high resolution imaging. A promising technique for backside illuminated devices is self-aligned etching of the mesas, or using the metal contact pad as the etch mask. In this work, we report on the self-aligned etching of two Type-II superlattice materials and some of their constituent material components to create pixels with subwavelength dimensions in a longwave infrared detector. Palladium was used as the primary mask material to prevent the exposure of the gold contacts to the etch plasma. The inductively coupled plasma conditions were varied, including varying the etch gas composition through different ratios of BCl₃ and Cl₂, and the etch rate and sidewall angle were measured. Using a mixture of BCl₃ and Cl₂ produced higher etch rates at room temperature than previously reported results at high temperatures with similar sidewall angles, thus reducing undesired diffusion of the device stack layers.

Small pixel pitch sensors offer opportunities for imaging system SWaP reduction that open up a variety of SWaP-constrained applications that were not previously feasible. Furthermore, small pixel digital sensors provide advantages in the form of additional SWaP reduction, noise immunity, and simplified interfacing requirements. With these motivations in mind, Attollo Engineering has developed a 640x512, 5μm pixel pitch, high operating temperature MWIR sensor based on III V compound semiconductor detector materials. We have adapted our 5μm pixel pitch SWIR processes for MWIR detector materials and have been able to achieve 99.5+% operability MWIR FPAs with BLIP performance operating at 130K. Additionally, we have developed a compact camera core with an integrated cooler and full featured camera electronics. The global shutter camera is capable of frame rates of up to 220 Hz or smaller windows in excess of 1 kHz and integration times as low as 100 nanoseconds. Attollo will discuss characteristics of this sensor and other related technologies.

There is a lot of interest in developing low noise avalanche photodiodes (APDs) in the short wave infrared (1.5-3 microns) and mid-wave infrared (3-5 microns). State of the art APDs are are based on based on interband transitions in mercury cadmium telluride (MCT, HgCdTe) with large multiplication gains and low excess noise factors due to the favorable bandstructure that promotes single carrier impact ionization. However, their dark currents are high (3-5e-4A/cm2 at a gain of 10 at 125K) that requires cryogenic cooling. We have investigated the multiplication characteristics of three different multipliers on InP substrate (AlGaInAs (M1), AlGaAsSb (M2) and AlInAsSb (M3)). We have demonstrated decrease in the excess noise factors using ternary superlattices and extremely low excess noise factors (k~0.01) and low dark current density (~10 A/cm2) at 300K. We will discuss the research challenges associated with the design, growth, fabrication and radiometric characterization of these APDs

In this presentation, we will report our recent efforts in achieving high performance in Antimonides type-II superlattice (T2SL) based infrared photodetectors using the barrier infrared detector (BIRD) architecture. The high operating temperature (HOT) BIRD focal plane arrays (FPAs) offer the same high performance, uniformity, operability, manufacturability, and affordability advantages as InSb. However, mid-wavelength infrared (MWIR) HOT-BIRD FPAs can operate at significantly higher temperatures (<150K) than InSb FPAs (typically 80K). Moreover, while InSb has a fixed cutoff wavelength (~5.4 μm), the HOT-BIRD offers a continuous adjustable cutoff wavelength, ranging from ~4 μm to <15 μm, and is therefore also suitable for long wavelength infrared (LWIR) as well. The LWIR detectors based on the BIRD architecture has also demonstrated significant operating temperature advantages over those based on traditional p-n junction designs. Two 6U SmalSat missions CIRAS (Cubesat Infrared Atmospheric Sounder) and HyTI (Hyperspectral Thermal Imager) are based on JPL’s T2SL BIRD focal plane arrays (FPAs). Based on III-V compound semiconductors, the BIRD FPAs offer a breakthrough solution for the realization of low cost (high yield), high-performance FPAs with excellent uniformity and pixel-to-pixel operability. We have also exploring the possibilities of integrating either metasurface resonator cavity or metasurface based flatlens with individual pixels to improve the signal-to-noise ratio of the detectors. Furthermore, we will discuss the advantages of the utilization of all digital read out integrated circuits with HOT-BIRDs.

We present the development status of Type II superlattice infrared detector (T2SL) for future space applications in JAXA. Space-borne infrared detectors require higher sensitivity, higher resolution, and larger formats than ground-based infrared detectors. The Geostationary Earth observation satellite is one of mission candidates to adopt T2SL for infrared sensor. In order to meet more demanding for such mission requirements, JAXA has developed T2SL. T2SL has preferable characteristics in terms of operating temperature and spectral sensityivity in the range of near infrared to very long wavelength infrared region. In this presentation, we report the development history of T2SL focal plane array in JAXA.

SCD introduced its first cooled two-dimensional (2D) Mid-Wave Infrared (MWIR) detector more than twenty years ago. The InSb Focal Plane Array (FPA) had a 30 μm pitch and approximately 80,000 pixels. We have since introduced 2D MWIR detectors with pitches of 25, 20, 15 and 10 μm and an increasing number of pixels, up to 3 M-pixel. By decreasing the pixel size, it is possible to increase their overall number in a given die size, leading to a higher resolution and opening the way for new applications such as persistent surveillance. On the other hand, maintaining the same number of pixels leads to a much smaller die size, which enables detectors to be manufactured with a lower Size, Weight, Power and Cost (SWaP-C). Reducing the pixel dimensions can also reduce the size of the optics to support lower SWaP-C at the system level. The novel XBn-InAsSb technology enables High Operating Temperature (HOT) MWIR FPA, normally operated at 150K, for lower SWaP and longer lifetime cooler, detector and system. To date, HOT MWIR detectors of several formats, with 15 and 10 μm pitch, are integrated in numerous electro-optical systems for many defense and commercial applications. Achieving even smaller pixel size while maintaining the same electro-optical performance, namely high quantum efficiency, low dark current, low cross talk, and high array uniformity, is a serious technological challenge. In this work, we present SCD's new HOT MWIR detector (CRANE) with 2560×2048 format and 5μm pitch.

Midwave infrared (MWIR) type-II superlattices (T2SL) have revolutionized the market with possibility of low Size, Weight and Power (SWaP) detectors. IRnova currently has a full-scale production of SWaP T2SL detectors (Oden MW, 640×512 on 15μm pitch), which have demonstrated excellent performance for operating temperatures up to 110 K at F/5.5. Development of high-resolution detectors with small pixel pitch (HD, 1280×1024 pixels) for MWIR as well as long wave and very long wave infrared (LWIR/VLWIR) detection is currently ongoing. In this paper, it has been demonstrated that the low dark current density and high sensitivity needed for high operating temperatures are maintained also for these small pixel pitch detectors, which makes IRnova’s T2SL technology fully compatible with next generation HD detectors.

High operating temperature(HOT) is the key for low size, weight and power(SWaP) detector development and SWaP detector is the key for modern weapon system such as unmanned aerial vehicle(UAV) and man portable system. The low dark current that determines the operating temperature can be achieved by adopting InAs/InAsSb type-II superlattice(T2SL) absorber and nBn structure. In this work, HOT mid-wavelength infrared(MWIR) detector with InAs/InAsSb T2SL absorber and AlAsSb barrier was developed. The AlAsSb barrier shows excellent lattice match with GaSb substrate. Only the dry etch for pixel reticulation was applied to fabricate the device. At 80 K, dark current density is 2e-9 A/cm2 at the bias -0.2 V and, at 130 K, 2e-7 A/cm2 at the bias -0.1 V. The quantum efficiency was measured for both front side illumination and back side illumination. The back side illumination offers higher quantum efficiency than the front side illumination. The average quantum efficiency is about 50 % for front side illumination with 3 μm absorber. The 640 x 512 VGA format focal plane array(FPA) with 15 μm pitch was fabricated to study the temperature dependency of electro-optical characteristics. It was found that mean noise equivalent temperature difference(NETD) below 150 K is 15 mK, which is limited by the well capacitance. As the temperature increases NETD increases proportional to the dark current.

High performance infrared focal plane arrays (FPAs) play a critical role in a wide range of imaging applications. However the high cost associated with the required cooling and serially processed die-level hybridization is major barrier that has thwarted Mid-wavelength Infrared (MWIR) detector technology from penetrating largevolume, low-cost markets. Under the Defense Advanced Research Projects Agency (DARPA) WIRED program, the HRL team has developed a wafer level integration schemes to fabricate large format Antimonidebased MWIR FPAs on Si Read Out Integrated Circuit (ROIC) as a means to achieve significant fab cost reduction and enhanced production scalability. The DARPA-hard challenge we are addressing is the thermal and stress management in the integration of two dissimilar materials to avoid detector and ROIC degradation and to maintain structure integrity at the wafer scale. In addition, a digital ROIC with extremely large well capacity was designed and taped-out, in order to increase the operating temperature of the FPAs. In this talk, we discuss our progress under the DARPA WIRED program.

After years of progress, GaSb based mid-wave infrared (MWIR) devices have moved from development into manufacturing. To accommodate this maturation, the Molecular Beam Epitaxy (MBE) growth of the MWIR photodetector structures has progressed to a production mode. By necessitating many repetitions of a given growth structure, the increase in volume has enabled the use of Statistical Process Control (SPC) techniques to improve command over critical parameters, and thereby improve the yield and throughput. These products have been grown on GaSb substrates using large format, multi-wafer platens for 100 mm and 125 mm diameter substrates in a Veeco Gen2000 MBE system. The material properties were measured by Atomic Force Microscopy (AFM), High-Resolution X-Ray Diffraction (HRXRD), Photoluminescence (PL), and diode performance (turn-on voltage, dark current (JD), Quantum Efficiency (QE), and cutoff wavelength). Analysis of the run-to-run data will be presented to exhibit the manufacturability of these structures.

We describe uncooled infrared focal plane arrays (IRFPAs), which consist of pn junction diodes fabricated on a silicon-on-insulator (SOI) layer using a complementary metal oxide semiconductor (CMOS) process. Based on this technique, we released the Mitsubishi Electric Diode Infrared sensor (MelDIR) into the thermal detector market in 2019. This sensor is an 80×32 IRFPA with a 25 μm pixel pitch, utilizing a chip-scale vacuum-packaging process. To reduce the sensor cost, we developed a common differential circuit that switches the column pixel line, and achieved a significant reduction in chip area. In order to use a low-cost lens in the sensor module, we also developed an aberration correction method that improves the temperature measurement accuracy. Furthermore, we evaluated the effectiveness of a shutter-less method based simply on the thermal behavior of the SOI diode. These techniques allow enhanced performance of the MelDIR.

Size, weight, power and cost reduction in thermal image sensors has become key to address high-volume applications. LYNRED, with its strong experience in manufacturing thermal image sensors, has developed a prototype of an IR image processor (ISP) to achieve the highest level of thermal imager integration (e.g. System in Package). This ISP (Image Signal Processor) is a dedicated ASIC built to apply a pipeline of image processing algorithms to the raw data from the Focal Plane Array (FPA). This processing corrects pixel defects and non-uniformities of the FPA, without requiring an external mechanical shutter. With this proof of concept, LYNRED demonstrates an easy-to-use, low power and compact plug-and-play thermal image solution.

Since the outbreak of SARS (2003) / new influenza (2009) / MARS (2013) and so on, thermography-based Fever Screening has been adopted in quarantine of airports and ports as a measure to prevent from the spread of infection. However, the fever judgement has been achieved with the experienced quarantine officer. Due to recent spread of COVID 19, installation of thermography is expanding not only to quarantine at airports and ports, but also to hospitals, schools, retail stores, various facilities, and sports/event venues. Automated fever screening system with high accuracy are needed. Generally, a thermometer that measures axillary or sublingual temperature is used for body temperature measurement accurately, but this method takes time and contacts the subject to measure. So it is not suitable for the screening. On the other hand, thermography, which can measure the temperature of several persons in real time in a non-contact manner, satisfies screening requirements, but the body surface temperature of the exposed part such as the face that can be measured, is strongly affected by the environmental temperature and fluctuates. Therefore, it has a problem that it is difficult to determine the presence or absence of fever by setting a constant threshold value only. In order to realize the automation of screening with high accuracy and efficiency and make it easy for general users to understand, we will increase the measurement accuracy of the body surface temperature of thermography, identify the face and each landmark position from the image, and measure the temperature (body surface) of that part. The effects of the environment and individual difference are corrected from the temperature of multiple specific parts, and the high-precise body temperature estimation is carried out, and the algorithm is further improved.

Thermopile Arrays for IR Imaging and body temperature screening applications Schieferdecker, J.; Schnorr, M., Forg, B.; Herrmann, F., Schmidt, C.; Leneke, W.; Simon, M.: Heimann Sensor GmbH, Maria-Reiche-Str. 1, 01109 Dresden, Tel. +49-351-888885-0; info@heimannsensor.com; In first part of this paper we describe, how fast the lower resolution thermopile arrays could be integrated into body temperature screeners to fight against COVID-19 pandemic spread. Second part will introduce first thermopile arrays with 60 µm pixel size, which allow to extend the application range into thermal Imaging and surveillance. All necessary signal conditioning and readout electronics including SPI interface are monolithically integrated on the sensor chip and allow thermopile arrays up to 120x84 pixels to fit in a standard TO-8 housing. Most thermopile arrays going into the body temperature screeners using simple 32x32 arrays with a single Ge lens using special coating for the 8-14 µm range. Due to small chip, simple fix focus optics and no need for vacuum packaging, they could be produced in very high volumes. Due to low pixel count, the screening was only for one person in narrow range up to about 1 m or so – sufficient for building entrance control. 80x64 arrays were bigger and more costly, but could be used to measure temperatures at up to 3 or 4 persons simultaneously. The digital output via SPI interface reduces the number of necessary connections of both 80x64 and the new 120x84 arrays to 6-pin only. Thanks to integrated 16 Bit AD converters on-chip the sensor arrays can be operated with Frame Rates up to 12 Hz (full resolution) and allow a very wide dynamic range with object temperatures up to 1000 °C. Higher frame rates are possible with setting the ADC resolution to 15 or 14 Bit. Since the new 120x84 array chip has 60 µm pixels vs the 90 µm pixels of the 80x64, both chips come with similar focal plane and chip sizes. Due to their identical SPI interface both chips can be mounted in same housing with same optics, giving rise to a “drop in” solution. Thermopile arrays are low cost but quite efficient sensors in 2020 fighting the COVID-19.

The COVID-19 pandemic has caused a renewed interest in Elevated Skin Temperature (EST) screening systems using infrared cameras. A standard for infrared EST system performance exists (IEC 80601-2-59) but few commercially available systems meet all the performance requirements of this standard. FDA researchers [Ghassemi et al.], in 2018, tested two commercially available EST systems to the IEC standard. They concluded the systems largely met the IEC standards but identified several ambiguities in the standard and, for some tests, proposed alternate test methods and criteria. Later they used these two systems in a large-scale clinical study testing the effectiveness for fever screening by comparing to oral temperature measurements [Zhou et al.]. In this paper we review the Ghassemi IEC test results and build on their work by recommending even further changes and clarifications to the IEC standard. Rationale for the recommended changes is illustrated with example test data collected using a prototype EST system. We also present a detailed treatment of how to do a complete system uncertainty analysis for these systems, identifying some inconsistencies in earlier treatments. The IEC standard includes requirements for accuracy, drift, stability, image uniformity, MRTD, spatial resolution and system uncertainty analysis. Ghassemi proposed an alternate test method and criteria for uniformity based on an “allpixel standard deviation” approach. We tested a prototype EST system to the IEC 80601-2-59 standard and with the alternate tests suggested by Ghassemi. We review pros, cons and limitations of each method and show how a 3D system noise approach (2D spatial plus temporal) can be used to mitigate limitations of both prior methods. From our results and review of Ghassemi we conclude that one of the two systems tested by Ghassemi likely did not meet the IEC specifications as presently written. Considering the very similar (and favorable) clinical results found by Zhou when they tested the two Ghassemi systems, we conclude the IEC standard as written is too stringent in some areas. In other respects, we found it has gaps and ambiguities. Some of these likely arose from attempts to address early interpreted-EST systems that relied on an operator to interpret the thermal image of the subject and make a subjective fever/no-fever determination. In hopes of improving the IEC standard, we recommend several changes.

Linked by ESA’s Astronomy Large Format Array for the near-infrared ("ALFA-N") technology development program, CEA and Lynred aim at setting up the fabrication of very large IR focal plane arrays (FPA) for astronomy needs. Prior to this project, dark current and image persistence are under investigation for achieving the high level of performance needed by astronomers. During previous characterization of this kind of detector, the FPA appeared particularly sensitive to ROIC electro-luminescence, preventing to observe fainter effects such as persistence. With the mitigation of the glow, the first measurements showed that dark current was dominated by persistence instead of classical diffusion, Auger or Shockley- Read-Hall mechanisms. We propose a dedicated test protocol in order to electrically characterize persistence and an empirical modelling tool to describe it in terms of amplitude and characteristic time constant. The first step consists in removing the residual persistence, allowing to characterize the intrinsic photodiode’s dark current, down to 0.03e-/s at 90K on four tested devices. From this reference, the persistence contribution is dramatically minimized and experimental conditions are reproducible, enabling further investigation on persistence to be carried out. Applied on detectors manufactured in the CEA-LETI clean rooms, this protocol aims at a better understanding of the phenomenon. Using an array containing different diode flavours (ie variations in the technological parameters such as diode geometry, passivation…), the characterization scheme described above should bring information about technological contributions on persistence.

N-on-p extrinsically doped MWIR HgCdTe material and photodiodes have been developed to benefit from the expected reduction of the Auger generation in the p-type absorbing layer. Samples with two doping levels have been characterized using dark current, current noise, Hall effect and PhotoLuminescence Decay (PLD) measurements. The dark current and PLD measurements are consistent with a reduction of the Auger generation quantified by the ratio between the Auger 1 and 7 recombination coefficients 𝛾 around 10. The corresponding dark current in the sample with the lowest doping level was slightly higher than in typically p-on-n photodiodes. The low frequency noise, characterized by a Tobin coefficient below 10^-5, is lower than the values reported for other MWIR HgCdTe photodiodes at the same dark current density. The low dark current and dark current noise show on the high potential of such photodiodes to form focal plane array that can be operated at high operating temperature without degradation of the image quality.

In the past century, optical functions were integrated onto the visible detectors. Nowadays, most of the visible detectors used for imagery are characterized by a large format, a small pixel pitch and RGB (Red-Green-Blue) filters. In the infrared bands of interest, the mid-wave infrared range (MWIR) can be divided in two sub-bands. The wavelengths associated to the MWIR blue band are ranging from 3.0 up to 4.2 μm and the red band from 4.2 up to 5.1μm. LYNRED and Safran Reosc are developing a new technological brick to integrate two optical functions onto a MWIR focal plane array. The objective of these optical functions is to increase the accuracy of detection minimizing the false alarms. These optical functions are realized onto the FPA like a chess board. On the one hand, half of the pixels are using an antireflective coating. On the other hand, the other pixels are filtered with a high pass filter. As a consequence, the first type of pixels has the ability to detect photons in the entire MW spectral range whereas the others are able to detect in the red band only. A first demonstrator has been realized using this new concept associated to a HgCdTe MW infrared detector. The performances are very promising with very low NETD (below 20mK) in both bands and a spectral crosstalk per pixel of 7.7%. A high operability has been demonstrated in both bands (> 99.5%). The reliability of this technological solution has been evaluated with success. Based on the heritage of Daphnis, a 10μm pitch product, LYNRED envisions a new one using this dual-color technological brick like an add-on onto the FPA. Thanks to the outstanding Modulation Transfer Function performance of the Daphnis, and a specific design of the micro-pattern structure of the filters, the spectral performances should significantly be improved.

QWIPs are renowned for unmatched image uniformity and stability. Still, in popular belief they are often associated with only stationary platforms due to low operating temperature and quantum efficiency. Challenging this myth, we demonstrate the performance of VLWIR QWIP in such demanding applications as handheld camera for gas detection and microsatellite for remote sensing. In the former, NETD of <25 mK is routinely achieved on 15 μm pitch sensor (target 30 C, 30 Hz frame rate, F/1.2, 10.5 μm peak absorption) consuming <9 W. In the latter, the 30 μm pitch array has two IR channels (10 and 10.8 μm) employing monolithically integrated bandpass filters. IDDCA delivers NETD <50 mK for 2 ms integration time (17 °C target, F/1.2) consuming 10 W. It comprises technology demonstrator for evaluating the use of microsatellites for precise temperature monitoring in Earth Observation applications. Stability of its non-uniformity correction, which is paramount for space-born applications, is also demonstrated.

There is a growing interest in low-cost small-format infrared array sensors. In this study, we demonstrate the properties of small-format graphene infrared array sensors. The devices consisted of 9 x 9 pixels, which were composed of graphene field-effect transistors (FETs) and graphene/semiconductor Schottky barrier diodes (SBDs). The photoresponses of these devices were evaluated under middle-wavelength infrared (MWIR) light irradiation. The graphene FETs exhibited ultrahigh responsivity owing to modulation of the field-effect and surface carriers caused by photocarriers generated in photosensitizers. The MWIR photoresponse of the graphene FETs was enhanced by photogating. Compared to the FETs, the SBDs showed improved dark current characteristics. The photocarriers injected into the graphene were amplified by the photogating effect induced in the graphene/insulator region. Line-scan MWIR images and profiles were obtained; the devices were mounted in ceramic image sensor packages and vacuum-cooled. They were then exposed to a scanning blackbody light source, and the MWIR photoresponse was evaluated. The photocurrent linearly increased with the step shift of the blackbody source. The results obtained in this study will contribute to the development of high-performance graphene-based IR image sensors.

Graphene—atomically thin carbon sheets with a two-dimensional hexagonal lattice structure—exhibits unusual electronic and optical properties. Photodetectors are a good prospective application of graphene because they should ideally exhibit a broadband photoresponse from the ultraviolet to terahertz regions and high-speed operation, as well as be inexpensive to produce. Numerous methods have been proposed in order to enhance the responsivity of graphene-based photodetectors. Among these methods, photogating is most promising because it can realize the highest performance. Photogating requires photosensitive layers at the vicinity of graphene in order to produce a voltage change. Various photosensitive layers, including quantum dots, Si, InSb, and LiNbO₃, are used in the visible to near-, mid-, and long-wavelength IR (NIR, MWIR, and LWIR) regions, respectively. However, the operating wavelength region is determined by the photosensitive layer, which undermines the advantage of broadband operation of the graphene. In this work, graphene nanoribbon (GNR) was used as a photosensitive layer. Graphene transistors were prepared using Si substrates with a SiO₂ layer and source and drain electrodes. Single-layer graphene fabricated by chemical vapor deposition was transferred onto this substrate and formed a channel, and GNR was formed on the graphene channel using a solution dispersion method. The photoresponse was measured in the mid- and long-wavelength infrared regions. The photoresponse was found to be enhanced by GNR photogating compared with the photoresponse of devices without GNR. These results are expected to contribute to the development of high-performance broadband IR photodetectors.

This study investigated the fabrication and performance of highly responsive photodetectors, constructed of turbostratic stacked graphene produced via chemical vapor deposition (CVD) and using the photogating effect. This effect was induced by situating photosensitizers around a graphene channel such that these materials coupled with incident light and generated large electrical changes. The responsivity of such devices correlates with the carrier mobility of the graphene, and so improved mobility is critical. This work assessed the feasibility of using turbostratic stacked CVD graphene to improve mobility since, theoretically, multilayers of this material may exhibit linear band dispersion, similar to monolayer graphene. This form of graphene also exhibits higher carrier mobility and greater conductivity than monolayer CVD graphene. The turbostratic stacking can be accomplished simply by the repeated transfer of graphene monolayers produced by CVD. Furthermore, it is relatively easy to fabricate CVD graphene layers having sizes suitable for the mass production of electronic devices. Unwanted carrier scattering that can be caused by the substrate is also suppressed by the lower graphene layers when turbostratic stacked graphene is applied. The infrared response properties of the multilayer devices fabricated in the present work were found to be approximately tripled compared with those of a monolayer graphene photodetector. It is evident that turbostratic stacked CVD graphene, which can be produced on a large scale, serves to increase the responsivity of photodetectors in which it is included. The results of this study are expected to contribute to the realization of low-cost, mass-producible, high-responsivity, graphene-based infrared sensors.

Mid-infrared (IR) laser spectroscopy is broadly used to study trace gas species in medical diagnostics, atmospheric monitoring, remote sensing, and industrial applications. Its capability to measure fundamental rovibrational bands due to the chemical functional groups in the most relevant gas molecules allows for high instrumental sensitivity. In this work, we used a target mid-IR wavelength laser diode to measure the concentration of CO₂ gas. In addition, detecting the weak mid-IR molecular absorption bands of gases like CO₂ at low concentrations requires increasing optical path lengths to be used. There are a number of methods that can potentially be used to lengthen the beam path in a spectroscopic system; the most obvious being to use a longer linear gas cell, which in some situations may suffice; however, space and volume requirements need to be considered. In this work, we used a circular multi-reflection (CMR) cell, which reflects the radiation back and forth through the sample medium multiple times greatly reducing the footprint size compared to a linear cell of equivalent path length. A CMR cell is designed and constructed so that it allows multi-reflections within the cell. The optical alignment of the cell and the convenience of changing the optical path length by adjusting its position with respect to the entering light beam are key advantages. This work will be used as the groundwork for designing an instrument for high-resolution measurement of gas abundances in planetary atmospheres.

Image fusion provides an attractive technical solution for surveillance applications, offering improved task performance for imaging systems. Through the fusion process, information from different spectral bands is combined to form a single video stream which gives an improved scene understanding together with an enhanced target detection and recognition capability. In this paper, ground-based surveillance requirements are used to define a tri-band image fusion camera comprising LWIR, NIR, and Visible spectral bands. The design approach used addresses both the performance and commercialisation challenges encountered in the development of an image fusion camera. These challenges are discussed in the context of earlier image fusion systems where useful lessons were learnt. Establishing an effective processing architecture is critical to image interpretation, and the functional design is presented. The tri-band camera design allows the user to view different image streams including enhanced single-band image data as well as both dual and tri-band fused imagery. Such flexibility enables the selection of the best imagery for specific scenarios and viewing conditions. The physical characteristics are a major constraint for handheld camera designs where the size, weight, and power limitations dictate both the choice of sensors as well as the processor card. For the design presented here, power consumption and latency figures are minimised using relatively simple arithmetical fusion algorithms which are combined with an adaptive colour weight map for regional optimisation. Example results are presented to illustrate the various technical challenges and trade-offs undertaken within this development programme.

Currently advanced MWIR camera systems’ shortcomings are related to 1) their high cost and being proprietary to large aerospace companies, 2) their compromise on power or frame rate, and 3) their compromise on noise and well capacity as the pixel pitch goes down and the array size is increased. This paper presents a novel low SWAP-C commercially available high-end MWIR camera system development. The camera incorporates a 10-micron pitch MWIR FPA with a 3- megapixel array size read out at full motion video rate, and even up to 90Hz rate. The small pitch sensor has various gain modes up to 20 million-electron well capacity as well as low noise at high readout rates delivering full 14-bit performance.

The development of Flexible Optoelectronic Organic Sensor for Infrared Detection (FOOS-IR), using an optically transparent substrate material and organic semiconductor materials, has been widely utilized by the electronic industry when producing new technological products. The greatest interest in studying organic semiconductor materials has been connected to its already known potential applications, such as: batteries, organic solar cells, flexible organic solar cells, organic light emitting diodes, organic sensors and others. Infrared is a type of electromagnetic radiation that has a frequency lower than that of red light and, therefore, is not within the visible electromagnetic spectrum. For this reason, this radiation cannot be perceived by the human eye. Infrared radiation originates from molecular vibration, which generates oscillations in the electrical charges that make up atoms and causes the emission of radiation, so this type of radiation is associated with heat. In this work, we developed a flexible organic optoelectronic sensor capable of detecting and determining the rate of radiation dose emitted by different sources of infrared radiation. The sensors were developed using optically transparent substrate with Nanostructured thin film layers of Poly(9-Vinylcarbazole) covered by a layer of Poly(P-Phenylene Vinylene) with nanostructured fullerene (C60) and Polyaniline-X1. The samples were characterized by UV-Vis Spectroscopy, Electrical Measurements and Scanning Electron Microscopy. With the results obtained from this study can be developed infrared sensitive OLEDs for applications in night vision systems and infrared technologies in security.

Infrared (IR) rectification is promising for high-performance IR detection at room temperature. We propose metal– insulator–metal (MIM)-based plasmonic structures incorporating a nanoslit for IR rectification. Gold and SiO₂ were used as the metal and insulator layers, respectively. A high-aspect-ratio nanoslit was incorporated onto the top of the metal layer of an MIM structure. This slit works as a coupler for incident IR light, and a surface plasmon mode is induced in the slit. The coupled IR light is then guided into the middle insulator layer and waveguide modes are formed. Rectification can be achieved by applying a voltage between the top and bottom metal layers. Finite-difference timedomain calculations show that wavelength selective detection can be achieved by controlling the slit width or depth. However, these proposed structures are difficult to fabricate because a metal-based high-aspect-ratio nanoslit cannot be formed by conventional dry or wet etching. We have developed fabrication procedures using gold electroplating and chemical mechanical polishing (CMP). The former method uses a photoresist as a sacrificial layer for the narrow slit, and the top metal is formed by electroplating. The latter uses SiO₂ as a sacrificial layer, and the top metal is formed by sputtering and CMP. Both methods can be used to fabricate an MIM structure with a nanoslit. It was found that the CMP method can achieve a higher aspect ratio. These proposed structures and fabrication techniques could contribute to the development of novel IR detectors using plasmonic rectification.

Nowadays, infrared (IR) photodetectors are mainly made from compound semiconductors due to the bandgap flexibility. However, compound semiconductors are mostly synthesized by expensive and energy-intensive epitaxy processes. Moreover, compound semiconductors are difficult to integrate with Si-based IC industry. Therefore, we used n-type Si (n-Si) wafers and thin NiSi to combine with localized surface plasmon resonance (LSPR) to form a Schottky IR detector. The incident IR light can induce thermionic effect to generate photocurrent, and the LSPR can enhance the light absorption and improve the photoresponse. The LSPR was created by NiSi covered inverted-pyramid array structures (IPAS) formed on n-Si substrates through photolithography and etching processes. After IPAS were prepared, 10-nm-thick Ni was thermally deposited on the IPAS and then the entire samples were annealed under 500 °C in 5 s to form NiSi/n-Si Schottky junctions. Finally, Ti and Au were thermally deposited successively on the NiSi and the back of n-Si wafers to be electrodes. A planar device was also prepared to be a control part. The photodetection ability of the device was examined by a 4.8-μm IR source with 1.8-mW optical power, which is in the absorption range of carbon monoxide. The IR source was turned on/off for each 15 s. Consequently, the planar NiSi/n-Si Schottky photodetector shows average 9.37-μA current change under 4.8-μm IR source illumination in 15 s. However, if 8-μm-period IPAS was used, the average current change improved to 30.9 μA. The response enhancement is 3.30 times of the planar device.

Molecular dynamics (MD) modeling of hydrogen-bond oscillations is described. Hydrogen-bonding plays an important role in interactions of molecular structures, and is associated with distinct features in vibrational spectra of molecular systems. Interpretation of these features is essential for monitoring and control of structural changes and kinetic processes in large ensembles of molecular structures. Computational experiments based on MD provide interpretation of vibrational-spectrum features. In the case of molecular binding spectroscopy, hydrogen-bond vibrational modes, which are associated with sorbent-sorbate interactions, can be correlated with characteristic spectral features at finite temperature.

We report our recent work on the fabrication of type-II superlattice (T2SL) LWIR nBn photodetectors. It is well known that the dangling bonds or the oxidized element on the etched mesa sidewall increase a dark current. Therefore, the passivation and treatment process for the mesa surface is the key for detector performance. In this work, we present an in-situ surface plasma treatment after the dry-etch process for the pixel isolation. To investigate the effects of the plasma treatment for the various gases (CHF₃, H₂, and H₂/Ar), the optical and electrical analysis were performed. The results show that H₂/Ar plasma treatment was effective for removing Sb-oxides at dry-etched surface. The fabricated devices which was measured at -0.1 V and 80 K shows the dark current density of -3.9 ｘ 10^-6 A/cm^-2 .

The deep mesa process for pixel isolation with ICP-RIE (Inductively Coupled Plasma – Reactive Ion Etching) was studied to develop InAs/GaSb type-Ⅱ superlattice (T2SL) LWIR photodetector with nBn structure. To reduce the lateral diffusion current component of the dark current components, it is essential to accomplish a proper deep dry etching process that can completely isolate absorption layer. In this work, ICP-RIE dry etching was studied to implement the smooth, vertical and isolated pixels. By increasing substrate temperature and adjusting the ratio of Ar in BCl₃/Ar gas, it was found that the etch rate was largely increased and mesa shpae has become perpendicular and smooth. It was also found that dark current density was increased as the surface roughness increased. For the best sufrgace roughness, the dark current density of 15 μm pitch device fabricated exhibited 4.92x10^-6 A/cm² at and applied bias of -0.1 V and a temperature of 80 K.

We report the noise characteristics of an AlInAsSb avalanche photodiode (APD) on an InP substrate. We observe low excess noise corresponding to an impact ionization coefficient ratio (k) of 0.012, and a dark current density of 55 μA/cm2 at a gain of 10 at room temperature. The performance of commercial APDs on InP substrates is limited by the excess noise and the performance of state of the art (SOA) APDs on InP substrates is limited by the dark current. The combination of low excess noise and low dark current of AlInAsSb leads to a significant performance improvement compared to commercial APDs and provides a potential candidate for low noise, SOA, commercial APDs for near-infrared applications. When combined in a separate absorber, charge and multiplication layer (SACM) architecture with an InGaAs absorption layer, the low noise characteristics of AlInAsSb point towards a superior InP substrate-based APD targeting 1.55 μm for applications such as optical communications and light detection and ranging (LiDAR).