Dr. Christian P. Morath Profile

Dr. Christian P. Morath

Research Physicist at Air Force Research Lab

SPIE Involvement:

Author

Publications (44)

Proceedings Article | 1 November 2024 Presentation + Paper

Analysis of surface currents in pBpn superlattice infrared detectors

Julie Logan, Alexander Newell, Rigo Carrasco, Preston Webster, Christian Morath

Proceedings Volume 13200, 132000C (2024) https://doi.org/10.1117/12.3031206

KEYWORDS: Sensors, Dark current, Quantum detection, Superlattices, Quantum efficiency, Electrons, Diffusion, Doping, Signal detection, Photons

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Proceedings Article | 1 November 2024 Presentation + Paper

Performance evaluation of a single pixel event-based sensor pixel unit cell optimized for mid-wave infrared sensing

Z. Alsaad, J. Logan, C. Morath, P. McMahon-Crabtree, L. Kulesza, D. Maestas, P. Zarkesh-Ha, P. Webster

Proceedings Volume 13200, 132001K (2024) https://doi.org/10.1117/12.3031209

KEYWORDS: Sensors, Transistors, Photodetectors, Photocurrent, Infrared sensors, Mid infrared, Logic, Signal detection, Signal processing

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Proceedings Article | 12 March 2024 Presentation

Microscopic-physics model for interface-roughness scattering and nonlinear electron transport in superlattice

Danhong Huang, Po-Hsin Shih, Godfrey Gumbs, Thi-Nga Do, Christian Morath, Tanya Maestas

Proceedings Volume PC12880, PC1288003 (2024) https://doi.org/10.1117/12.2690859

KEYWORDS: Scattering, Superlattices, Electron transport

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Proceedings Article | 3 October 2023 Presentation + Paper

Event-based camera refractory period characterization and initial clock drift evaluation

Peter McMahon-Crabtree, Lucas Kulesza, Brian McReynolds, Daniel O'Keefe, Anirvin Puttur, Diana Maestas, Christian Morath, Matthew McHarg

Proceedings Volume 12693, 126930V (2023) https://doi.org/10.1117/12.2672301

KEYWORDS: Cameras, Clocks, Sensors, Commercial off the shelf technology, Integrating spheres, Light sources, Monte Carlo methods, Light emitting diodes, Modulation, Visualization

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Event-based camera (EBC) technology provides high-dynamic range operation and shows promise for efficient capture of spatio-temporal information, producing a sparse data stream and enabling consideration of nontraditional data processing solutions (e.g., new algorithms, neuromorphic processors, etc.). Given the fundamental difference in camera architecture, the EBC response and noise behavior differ considerably compared to standard CCD/CMOS framing sensors. These differences necessitate the development of new characterization techniques and sensor models to evaluate hardware performance and elucidate the trade-space between the two camera architectures. Laboratory characterization techniques reported previously include noise level as a function of static scene light level (background activity) and contrast responses referred to as S-curves. Here we present further progress on development of basic characterization methods and test capabilities for commercial-off-the-shelf (COTS) visible EBCs, with a focus on measurement of pixel deadtime (refractory period) including results for the 4th-generation sensor from Prophesee and Sony. Refractory period is empirically determined from analysis of the interspike intervals (ISIs), and results visualized using log-histograms of the minimum per-pixel ISI values for a subset of pixels activated by a controlled dynamic scene. Our tests of the Prophesee gen4 EVKv2 yield refractory period estimates ranging from 6.1 msec to 6.8 μsec going from the slowest (20) to fastest (100) settings of the relevant bias parameter, bias_refr. We also introduce and demonstrate the concept of pixel bandwidth measurement from data captured while viewing a static scene – based on recording data at a range of refractory period setting and then analyzing noise-event statistics. Finally, we present initial results for estimating and correcting EBC clock drift using a GPS PPS signal to generate special timing events in the event-list data streams generated by the DAVIS346 and DVXplorer EBCs from iniVation.

Proceedings Article | 30 September 2022 Presentation + Paper

Automated characterization techniques and testbeds for event-based cameras

Peter McMahon-Crabtree, Wellesley Pereira, Robert Crow, Richard Preston, Lucas Kulesza, Ryan Crowell, Christian Morath, Diana Maestas, Zachry Theis, Patricia Sablan

Proceedings Volume 12233, 122330B (2022) https://doi.org/10.1117/12.2634166

KEYWORDS: Sensors, Cameras, Reliability, Gamma radiation, Aerospace engineering, Optical testing, Ionizing radiation effects

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Event-based camera (EBC) technology shows promise for efficient capture of spatio-temporal information, producing a sparse data stream and enabling consideration of nontraditional data processing solutions (e.g., new algorithms, neuromorphic processors). Given the fundamental difference in camera architecture, the EBC response and noise behavior differ considerably compared to standard CCD/CMOS framing sensors. These differences necessitate development of new characterization techniques to quantify performance and assess if the EBC technology produces benefits relative to traditional imaging sensors. Here we present progress on development of basic sensor performance modeling and test capabilities for commercial-off-the-shelf visible EBCs. Laboratory characterization techniques include noise level as a function of static scene light level (termed background activity) and EBC temporal contrast response to dynamic signals. Initial environmental tests of the Prophesee PPS3MVCD event-based sensor found several addressable areas of concern but identified no showstoppers that would prevent use of this device in a high-reliability aerospace application. Two independent radiation tolerance test efforts, one for the PPS3MVCD and another for the iniVation DAVIS346 EBC (both based on 180 nm CMOS technology), indicate functional issues for total ionizing dose (TID) of greater than 30 krad(Si), and show background activity increasing with TID. However, no significant change in contrast response was observed. One DAVIS346 exhibited functional failure following final gamma radiation dose from 20 krad(Si) to 50 krad(Si), and the readout saturated during doses dominated by negative-polarity events (by a factor of 10 or greater). A second DAVIS346 locked-up during proton dose but recovered normal operation following a brief rest period and power cycling. DAVIS346 pixels include both change detection (DVS) and standard grayscale frames (APS) functionalities – driven by a single photodiode; results show a 70% increase in dark current and 23% increase in dark event noise after proton exposure to 20 krad(Si). As new versions of EBC technology are developed for infrared wavelengths, we anticipate these characterization techniques will be largely translatable to IR EBCs.

Proceedings Article | 30 May 2019 Paper

Comparing II-VI and III-V infrared detectors for space applications

Elizabeth Steenbergen, Christian Morath, Diana Maestas, Geoffrey Jenkins, Julie Logan

Proceedings Volume 11002, 110021B (2019) https://doi.org/10.1117/12.2519250

KEYWORDS: Quantum efficiency, Mercury cadmium telluride, Infrared detectors, Sensors, Photodiodes, Diffusion, Photodetectors

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Proceedings Article | 23 May 2018 Presentation + Paper

Vertical transport study of InAs/GaSb type-II superlattice nBp MWIR detectors using electron beam-induced current measurement

Z. Taghipour, E. Steenbergen, S. Maximenko, C. Morath, V. Cowan, S. Mathews, E. Aifer, G. Balakrishnan, S. Krishna

Proceedings Volume 10624, 106240N (2018) https://doi.org/10.1117/12.2309658

KEYWORDS: Diffusion, Mid-IR, Superlattices, Electron transport, Gallium antimonide

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Proceedings Article | 21 May 2018 Presentation + Paper

Carrier concentration and transport in Be-doped InAsSb for infrared sensing applications

Lilian Casias, Christian Morath, Elizabeth Steenbergen, Preston Webster, Jin Kim, Vincent Cowan, Ganesh Balakrishnan, Sanjay Krishna

Proceedings Volume 10624, 106240M (2018) https://doi.org/10.1117/12.2305431

KEYWORDS: Infrared detectors, Sensors, Doping, Infrared sensors, Photodiodes, Quantum efficiency, Interfaces, Electron transport, Gallium antimonide, Spectrum analysis

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Proceedings Article | 19 September 2017 Presentation

Effects of 4.5 MeV and 63 MeV proton irradiation on carrier lifetime of InAs/InAsSb type-II superlattices (Conference Presentation)

Emil Kadlec, Michael Goldflam, Edward Bielejec, Jin Kim, Benjamin Olson, John Klem, Samuel Hawkins, Johnathan Moussa, Peter Schultz, Christian Morath, Geoffery Jenkins, Vincent Cowan, Eric Shaner

Proceedings Volume 10404, 1040405 (2017) https://doi.org/10.1117/12.2274377

KEYWORDS: Mid-IR, Superlattices, Infrared detectors, Particles, Aerospace engineering, Radiation effects

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Proceedings Article | 30 August 2017 Presentation + Paper

Extraction of minority carrier diffusion length of MWIR Type-II superlattice nBp detector

Zahra Taghipour, Alireza Kazemi, Stephen Myers, Priyalal Wijewarnasuriya, Sen Mathews, Elizabeth Steenbergen, Christian Morath, Vincent Cowan, Gamini Ariyawansa, John Scheihing, Sanjay Krishna

Proceedings Volume 10404, 1040406 (2017) https://doi.org/10.1117/12.2274591

KEYWORDS: Quantum efficiency, Diffusion, Absorption, Temperature metrology, Sensors, Mid-IR, Superlattices, Gallium antimonide, Photodiodes, Diodes

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Proceedings Article | 16 May 2017 Paper

High quantum efficiency mid-wavelength infrared superlattice photodetector

Alireza Kazemi, Stephen Myers, Zahra Taghipour, Sen Mathews, Ted Schuler-Sandy, Seung Hyun Lee, Vincent Cowan, Eli Garduno, Elizabeth Steenbergen, Christian Morath, Gamini Ariyawansa, John Scheihing, Sanjay Krishna

Proceedings Volume 10177, 101771M (2017) https://doi.org/10.1117/12.2263879

KEYWORDS: Quantum efficiency, Photodetectors, Superlattices, Mid-IR, Infrared detectors, Sensors, Stereolithography, Quantum well infrared photodetectors, Infrared photography, Infrared radiation, Antireflective coatings

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Proceedings Article | 27 January 2017 Open Access

A recent review of mid-wavelength infrared type-II superlattices: carrier localization, device performance, and radiation tolerance

Elizabeth Steenbergen, Gamini Ariyawansa, Charles Reyner, Geoffrey Jenkins, Christian Morath, Joshua Duran, John Scheihing, Vincent Cowan

Proceedings Volume 10111, 1011104 (2017) https://doi.org/10.1117/12.2266040

KEYWORDS: Stereolithography, Sensors, Laser sintering, Mid-IR, External quantum efficiency, Indium arsenide, Gallium antimonide, Mercury cadmium telluride, Superlattices, Infrared detectors

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Proceedings Article | 7 December 2016 Presentation

Comparison of MWIR unipolar barrier structures based on strained layer superlattices (Conference Presentation)

David Ramirez, Stephen Myers, Yuliya Kuznetsova, Sen Mathews, Theodore Schuler-Sandy, Elizabeth Steenbergen, Christian Morath, Vicent Cowan, Sanjay Krishna

Proceedings Volume 9974, 99740C (2016) https://doi.org/10.1117/12.2239723

KEYWORDS: Superlattices, Mid-IR, Sensors, Structural design, Ionizing radiation, Silicon, Analytical research, Infrared sensors, Current controlled current source

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