This PDF file contains the front matter associated with SPIE Proceedings Volume 9170, including the Title Page, Copyright information, Table of Contents, Invited Panel Discussion, and Conference Committee listing.

Silicon nanowires (SiNWs) have emerged as a promising material for high-sensitivity photodetection in the UV, visible and near-infrared spectral ranges. In this work, we demonstrate novel planar SiNW phototransistors on silicon-oninsulator (SOI) substrate using CMOS-compatible processes. The device consists of a bipolar transistor structure with an optically-injected base region. The electronic and optical properties of the SiNW phototransistors are investigated. Preliminary simulation and experimental results show that nanowire geometry, doping densities and surface states have considerable effects on the device performance, and that a device with optimized parameters can potentially outperform conventional Si photodetectors.

Photo- and thermo-mechanical actuation behaviour in specific polymer-carbon nanotube composites has been observed in recent years and studied at the macroscale. These systems may prove to be suitable components for a wide range of applications, from MOEMs and nanotechnology to neuroscience and tissue engineering. Absence of a unified model for actuation behaviour at a molecular level is hindering development of such smart materials. We observed thermomechanical actuation of ethylene-vinyl acetate | carbon nanotube composites through in situ near-edge X-ray absorption fine structure spectroscopy to correlate spectral trends with macroscopic observations. This paper presents spectra of composites and constituents at room temperature to identify resonances in a building block model, followed by spectra acquired during thermo-actuation. Effects of strain-induced filler alignment are also addressed. Spectral resonances associated with C=C and C=O groups underwent synchronised intensity variations during excitation, and were used to propose a conformational model of actuation based on carbon nanotube torsion. Future actuation studies on other active polymer nanocomposites will verify the universality of the proposed model.

The organic nanostructured conducting polymer Poly (O-toluidine)/ Silicon nanowires (NPOT/SiNWs) heterojunction is investigated as a candidate heterojunction diode. For this purpose, NPOT/SiNWs heterojunction was fabricated through low cost and simple techniques. SiNWs were fabricated using improved metal-assisted electroless etching of Si substrates. NPOT thin film was chemically fabricated via in situ polymerization method. The morphology of SiNWs before and after deposition of NPOT was confirmed by scanning electron microscope (SEM). I-V measurements of the device were made at room temperature under dark conditions.

The characteristic temperature calculations and dependency on cavity length was analyzed for Pb_0.934Sr_0.066 Se multiple Quantum well Structure at three temperature ranges 77<T<150 K, 150<T<300 K, and 77<T<300 K. In this work, we show the behavior of the characteristic temperature as a function of cavity length and were able to best fit the data to a second degree polynomial. Inclusion of theoretical values for the quantum efficiency due to Auger recombination reduces the characteristic temperature T₀ in these ranges. It was found that inclusion of the quantum efficiency decreases the characteristic temperature by a factor of 0.6 for a wide range of cavity lengths. When results were compared to experimental data, it was concluded that there is a leakage current above the barrier due to thermionic emission. The leakage current density was estimated to be around 5423 A/cm² at room temperature. With this high value more work is needed to understand the thermionic emission process to improve on the performance of this material system and similar ones.

A custom micro-mechanical test system was constructed using off-the-shelf components to characterize the mechanical properties of microshutters. Microshutters are rectangular microelectromechanical apertures which open and close about a narrow torsion bar hinge. Displacement measurements were verified using both capacitive and digital image correlation techniques. Repeatable experiments on Si₃N₄ cantilever beams verified that the test system operates consistently. Using beam theory, the modulus of elasticity of the low stress Si₃N₄ was approximately 150 GPa, though significant uncertainty exists for this measurement due primarily to imprecise knowledge of the cantilever thickness. Tests conducted on microshutter arrays concluded that reducing the Si₃N₄ thickness from 250 nm to 500 nm reduces the torsional stiffness by a factor of approximately four. This is in good agreement with analytical and finite element models of the microshutters.

By dispersing graphene nanoplatelets (GNPs) within a polydimethylsiloxane matrix, we show that light absorption by GNPs and subsequent energy transduction to the polymeric chains can be used to controllably produce significant amounts of motion through entropic elasticity of the pre-strained composite. Using dual actuators, a twoaxis sub-micron resolution stage was developed, and allowed for two-axis photo-thermal positioning (~100 μm per axis) with 120 nm resolution (feedback sensor limitation), and ~5 μm s^-1 actuation speeds. A PID control loop automatically stabilizes the stage against thermal drift, as well as random thermal-induced position fluctuations (up to the bandwidth of the feedback and position sensor).

The unique optical properties of porous silicon show it to be a promising material for imaging and spectroscopy in the mid-infrared and long-infrared wavelength ranges. A tunable MEMS filter using porous silicon as a high-reflectivity layer is proposed. Measurements on fabricated porous silicon-based distributed Bragg reflectors and Fabry-Perot etalons are presented.

In this work we investigate the organic products of the synthesis of Co-based nanoparticles in benzyl alcohol. Our GC and in situ IR studies provide the experimental proofs for the formation of benzaldehyde, toluene and isopropanol in the reaction solution. These organic products can be correlated with formation of cobalt-based nanoparticles with oxidation state from 0 to 3+. These results shine the light on the complexity of organic and inorganic reactions in solution during crystallization of nanoparticles.

We report a CMOS compatible fabrication and optical characterization of the micrometer scale optical coupler, a 45° mirror-based optical coupler for inter-layer optical coupling. A newly proposed mask-based and mask-less hybrid lithography process enables accurate surface profile of the micrometer sized 45° mirror by using a CMOS compatible buffer coat material. Surface profile inspected by an optical interferometry agrees well with SEM based inspection results. Experimental and theoretical results for routing and coupling of laser beam in 90° will be discussed.

The possibility of novel nanocomposite materials with dramatically improved properties requires fundamental studies of interactions. Full elucidation of these concepts will allow the tailoring of such systems for particular applications. Using near-edge X-ray absorption fine structure spectroscopy, we investigated interactions in electrospun poly(dimethylsiloxane)-poly(methyl methacrylate)-multiwall carbon nanotube composites. This paper describes these interactions through a building-block model, addresses their dependence upon filler size, and discusses electrospinning as an alignment solution. Though alignment of filler and polymeric chains was not observed spectrally, SEM imaging confirmed uniaxial carbon nanotube alignment in composite fibres. Spectra acquired at different incidence angles revealed differences in energy and intensity of resonances, suggesting conformational configurations. These differences were more significant in composites with larger nanofiller. This supported proposed models of CH-π interactions and hydrogen bonding as adhesion mechanisms.

Ultrathin silver films (thickness below 10 nm) are of great interest as optical coatings on windows and plasmonic devices. However, producing these films has been a continuing challenge because of their tendency to form clusters or islands rather than smooth contiguous thin films. In this work we have studied the effect of Cu, Ge and ZnS as wetting layers (1.0 nm) to achieve ultrasmooth thin silver films. The silver films (5 nm) were grown by RF sputter deposition on silicon and glass substrates using a few monolayers of the different wetting materials. SEM imaging was used to characterize the surface properties such as island formation and roughness. Also the optical properties were measured to identify the optical impact of the different wetting layers. Finally, a multi-layer silver based structure is designed and fabricated, and its performance is evaluated. The comparison between the samples with different wetting layers show that the designs with wetting layers which have similar optical properties to silver produce the best overall performance. In the absence of a wetting layer, the measured optical spectra show a significant departure from the model predictions, which we attribute primarily to the formation of clusters.

We dispersed silver nanospheres of diameter 5nm in a homogeneous binder. Films were spin-coated on glass substrates. The transmission spectra of such films are measured as particle concentration is varied. The transmission spectra show deeper and wider minima in the shorter wavelength side as the concentration of nanoparticles increase. This might be explained by the formation of aggregates of nanoparticles and the coherent interaction among the constituent elements of the aggregates. The coherent interaction can include coupling among the localized surface plasmon resonance (LSPR) modes of individual particles. To explain the dependence of transmission spectra on the concentration of particles we computed the scattering properties of particle aggregates. The scattering properties of a single spherical particle can be computed analytically using Mie theory. No analytical computation method is available for aggregates of nanoparticles. Numerical methods, like finite-difference time-domain (FDTD) method can be used. We computed the scattering properties of aggregates of silver nanospheres using a monochromatic version of recursive convolution finite-difference time-domain (RC-FDTD) method. In contrast with the conventional broadband RC-FDTD [3], the monochromatic version allows one to use the handbook values of permittivity of the material of the particles at every simulation wavelength. The algorithm employs the 1st order Drude model to make it stable for metals with negative real part of permittivity. The particle-aggregates are generated using a random number generator that distributes nanospheres uniformly throughout a larger sphere made of the homogeneous binder medium.

Low noise mode-locked lasers and stabilized optical frequency combs are receiving considerable attention due to their broad spectrum of applications which ranges from signal processing to communications to metrology. Progress has been made in the realization of ultralow noise pulse trains by using ultralow expansion (ULE) quartz etalons for filtering the axial mode groups. An important step towards miniaturization of these systems is the integration of a high finesse on-chip optical filter that would serve to replace the ULE etalon. In this paper, we report our experimental results towards the realization of such a high finesse cavity based on a silicon microring resonator.

The development of nanotechnology gives new possibilities for fabrication of different x-ray optical elements. We present results of focusing properties the compound silicon linear Zone Plate (ZP) for first and second orders. The compound silicon linear ZP is fabricated by an electron beam lithography and lift-off technology. ZPs structures have been etched by ion-plasma up to 6μm deep. A linear ZP of the first and second orders fabricated for x-ray radiation 10kev energy, the focal distance is 57sm. The entire aperture is 357.64μm, the width of the outermost zones of the first and second orders are 595nm, and the number of the first and second order zones are: N(1) + N(2) = 251.The experiment was performed at the beam line BL29XU Spring-8 of the Japan Synchrotron Radiation Facility. The experimentally and theoretically investigations were done for x-ray energy at the 10keV and 12.4keV (0.1nm wavelength). The radial distribution of intensity is determined as a convolution of the zone plate transmission function and the Kirchhoff propagator in par-axial approximation. The algorithm is based on the FFT procedure and studied by means of computer programming simulation.

We demonstrate designs of dielectric-filled anti-reflection coated (ARC) two-dimensional (2D) metallic photonic crystals (MPhCs) capable of omnidirectional, polarization insensitive, wavelength selective emission/absorption. Up to 26% improvement in hemispherically averaged emittance/absorptance below the cutoff wavelength is observed for optimized hafnium oxide filled 2D tantalum (Ta) PhCs over the unfilled 2D Ta PhCs. The optimized designs possess high hemispherically averaged emittance/absorptance of 0.86 at wavelengths below the cutoff wavelength and low hemispherically averaged emittance/absorptance of 0.12 at wavelengths above the cutoff wavelength, which is extremely promising for applications such as thermophotovoltaic energy conversion, solar absorption, and infrared spectroscopy.

Extracellular Biosynthesis technique (EBS) for nanoparticles production has attracted a lot of attention as an environmentally friendly and an inexpensive methodology. Our recent research was focused on the rapid approach of the green synthesis method and the reduction of the homogeneous size distribution of nanoparticles using pulse laser application. Noble nanoparticles (NNPs) were produced using various ethanol and water plant extracts. The plants were chosen based on their biomedical applications. The plants we used were Magnolia grandiflora, Geranium, Aloe ‘tingtinkie’, Aloe barbadensis (Aloe Vera), Eucalyptus angophoroides, Sansevieria trifasciata, Impatiens scapiflora. Water and ethanol extract, were used as reducing agents to produce the nanoparticles. The reaction process was monitored using a UV-Visible spectroscopy. NNPs were characterized by Fourier Transfer Infrared Spectroscopy (FTIR), Transmission Electron Microscopy (TEM), and the Dynamic Light Scattering technique (DLS). During the pulse laser Nd-YAG illumination (λ=1064nm, 532nm, PE= 450mJ, 200mJ, 10 min) the blue shift of the surface plasmon resonance absorption peak was observed from ~424nm to 403nm for silver NP; and from ~530nm to 520 nm for gold NPs. In addition, NNPs solution after Nd-YAG illumination was characterized by the narrowing of the surface plasmon absorption resonance band, which corresponds to monodispersed NNPS distribution. FTIR, TEM, DLS, Zeta potential results demonstrated that NNPs were surrounded by biological molecules, which naturally stabilized nanosolutions for months. Cytotoxicity investigation of biosynthesized NNPs is in progress.

In this paper, we demonstrate a wiregrid polarizer for the near-IR spectrum fabricated by nanoimprint techniques. High resolution grating structures with 215nm in linewidth, 375nm pitch and 235nm total height were patterned on silicon by deep-UV interference lithography followed by reactive ion etching. The grating structures were transferred to a SU-8 thin film by nanoimprint. Then a glancing angle deposition was performed to build the wiregrids. The extinction ratio was measured to be over 90:1 at 1064nm.

The ability to control the position and orientation of nanorods in a device is interesting both from a scientific and a technological point of view. Because semiconductor nanorods exhibit anisotropic absorption, and spontaneous and stimulated emission, aligning individual NRs to a preferred axis is attractive for many applications in photonics such as solar cells, light-emitting devices, optical sensors, switches, etc. Electric-field-driven deposition from colloidal suspensions has proven to be an efficient method for the controlled positioning and alignment of anisotropic particles. In this work, we present a novel technique for the homogeneous deposition and alignment of CdSe/CdS NRs on a glass substrate patterned with transparent indium tin oxide interdigitated electrodes, with a spacing of a few micrometers. This method is based on applying a strong AC electric field over the electrodes during a dip-coating procedure and subsequent evaporation of the solvent. The reproducible and homogeneous deposition on large substrates is required for large size applications such as solar cells or OLEDs. The accumulation, alignment, and polarized fluorescence of the nanorods as a function of the electrical field during deposition are investigated. A preferential alignment with an order parameter of 0.92 has been achieved.

A novel design of single polarization single mode (SPSM) photonic nanowire is proposed. Using a cladding structure with circular air holes, a new design of a photonic nanowire with ultra-wideband range of 740 nm for SPSM operation is obtained. The numerical results show that the SPSM-nanowire is low-loss within the wavelengths ranging from 1.17 μm to 1.91 μm, the confinement loss of the slow-axis mode is less than 0.15 dB/km and the fast-axis mode is unguided. This fiber has greater advantages in polarization sensitive applications, such as fiber optic gyroscopes, fiber optic current sensors, high-power fiber lasers, and coherent optical communications.

Approximately spherical nanoparticles of the II–VI semiconductor materials Cd_1-xZn_xS have been produced successfully by laser ablation of the bulk material in several liquids. The non-stabilized suspensions of particles are characterized by absorption spectroscopy and transmission electron microscopy (TEM). The procedure is not strongly size-selective, radii of 7±3 nm were found for Cd_1-xZn_xS by transmission electron microscopy. Acetonitrile stabilizes the particles for several days up to weeks. Prolonged irradiation leads effectively to a reduction in particles size, in which particle agglomeration may play an important role. Ablation in degassed liquids does not have a significant effect on the absorption of the suspended particles.

Nano-fabrication technologies are usually associated with complication, high cost, and limited area of coverage. However, advances in optics and nanophotonics constantly demand novel fabrications for nano-manufacturing systems with extraordinary optical, electrical, mechanical, or thermal responses. While, these properties are vital for health, energy, and information technology applications, proposing new methods of fabricating nanostructures that can be compatible with high throughput and large scale manufacturing is quite desirable. Here, we propose a deep ultra-violet (DUV) photolithography technique that can produce a variety of periodic nanostructure clusters with sub-100 nm feature sizes. The method is based on microsphere nanolithography, which focuses DUV field into a socalled photonic nano-jet – a propagative intensive field underneath the sphere. The position of a photonic nano-jet can be moved by changing the angle of exposure. The DUV microsphere nanolithography is inherently self-aligned, mask-less and optics-less (the bulky optical element such as lens is not required), which makes this method attractive for low-cost and high-throughput nano-manufacturing schemes, such as roll-to-roll production. Here, we present fabricated arrays of nanoscale complex structures to demonstrate the capabilities of this nanolithography method.

The authors report a new process combining interference lithography with potassium hydroxide (KOH) anisotropic etch technique for fabrication of high aspect ratio silicon gratings on (110) oriented silicon wafers. This new process has the ability in fabricating high aspect ratio silicon gratings with extremely smooth sidewalls over a large sample area. An alignment method was developed to align interference fringes to the vertical (111) planes of (110) oriented wafers. In addition, a room temperature etch process with 50 wt % KOH solution was chosen to finally get an etch anisotropy of 188. Better etch uniformity was achieved by adding a surfactant to the aqueous KOH to promote the release of hydrogen bubbles. To increase latitude in KOH etching process, deposition of aluminum under a sloped angle with respect to the grating structures was utilized to obtain a high duty cycle nitride mask. To prevent the collapse of high aspect ratio grating structures caused by surface tension, a liquid carbon dioxide supercritical point dryer was used in the drying process. The authors successfully fabricated 320nm period gratings with aspect ratio up to 100 on 5-μm-thick silicon membranes on (110) oriented silicon-on-insulator wafers. The sample area is about 50 mm × 60 mm. The roughness (root mean square) of the sidewall is about 0.267 nm.

The structures consisting of Ge-nanoclusters grown on silicon oxide layer are promising candidates for optoelectronics as well as for nonvolatile memory circuits . This is due to their infrared photoluminescent and photoconductive properties. Crystalline germanium nanoclusters (NCs) are grown by a molecular-beam epitaxy technique on chemically oxidized Si(100) surface at 700°C. It was shown that structures with Ge-nanoclusters, grown on silicon surface characterized by fluctuations of the electrostatic field, that determined of positive charge trapped by dimensional quantum states Ge nanoclusters and Ge-nanoclusters/Si interface traps. Field effect on lateral conductivity and photovoltage spectra in Ge-nanostructures were analized.

We study nano-scale ITO top transmission gratings to improve light extraction efficiency using finite difference time domain (FDTD) method. Our study deals with a LED model with triangular-gratings and square-gratings. We achieve a 165.67% improvement for triangular ITO grating. Our study for square-gratings shows that it also can improve the total light extraction efficiency. Thus far, we have only achieved a 7.16% improvement with an ITO layer thickness of 230nm, a 230nm grating width and 10% duty cycle. We will present our comparison in further detail which will include various ITO layer thicknesses, grating widths and duty cycles.

Recently, ultrafast strong field induced optical current in SiO₂ dielectric medium has demonstrated. By foaming laser intensity more than 10¹³ W•cm^-2 in the dielectric material, the optical current was generated in a dielectric gap without any DC bias. This phenomenon is affected by the strength electric field of incident laser field and the generated electrons follow the speed of optical frequency enabling lightfast electronics in the future. In this study, we especially adopted nanoplasmonic field to trigger and control current flow in a nanometer spatial resolution. Nanoplasmonic field enables to manipulate light field in nanoscale domain. By using nanoplasmonic field, optically induced current flow can be selectively controlled by characteristic of nanoplasmonic nanostructure. For the first demonstration, saw tooth like 2-D nano Au pattern was numerically and experimentally investigated to boost up the laser intensity of incident 4.5 fs laser pulse with minimum field distortion and broadening. The intensity enhancement factor of plasmonic field at the saw tooth tip was ~40, enabling Wannier–Stark effect with incidence intensity level of only 10¹¹W•cm^-2 in the TiO₂ substrate. The carrier envelope phase of laser pulse is controlled to measure ultrafast optical current generation in dielectric medium by plasmonically induced strong near-field. This will be the basis for developing practical lightfast optical electronics in the future.

This paper presents a custom designed, fully automated UV holographic lithography system based on Lloyd‘s mirror interferometer geometry. This system was used to record large area (50×50 mm²) 1D and 2D periodic patterns with periodicity of 288 nm in a positive tone photoresist layer spin coated on crystalline silicon substrate. Produced structures were investigated with atomic force and scanning electron microscopes.

In this research, mono-dispersed quantum dots of CdSe were produced using a phosphine-free approach to synthesis of colloidal quantum dots. Selenium precursor was selected as the main precursor. It was found that the initial concentration ratio of monomers critically controlled the size distribution of the nanoparticles through its influence on the growth kinetics of these particles. The best result was obtained using an initial Se/Cd ratio of 5 where CdSe quantum dots of a uniform size were synthesized. This was manifested in the absorption spectra of these particles by occurrence of sharp peaks at a wavelength of about 615 nm.