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Intensive research for more than a decade has demonstrated that porous silicon (PSi) can be an excellent alternative material for multilayer optical devices, such as Bragg mirrors, microcavities and filters. In this paper, we shall describe a new application of PSi. We have designed, fabricated and tested various types of PSi based graded refractive index (GRIN) lenses. These planar micro-lenses are...
Time-resolved infrared spectrometry was conducted by using a PtSi focal plane array. A reflection grating dispersed the probe beam in the horizontal direction, and a galvano - mirror scanned the beam in the vertical direction. Consequently, the spectral and temporal data could be measured by the two-dimensional PtSi array. The spectra of the flowing gases were measured in the 2.8-4.6- mum wavelength...
Vertical tunneling photoconductivity in thick barrier GaAs/AlAs superlattice diodes has been experimentally investigated at 18 K as a function of electric field at high and low illumination powers by photocurrent (PC) response and photoluminescence (PL) measurements. For the thick barrier SL diode, PC spectra show unusual behaviors such as negative PC peaks at the maximum positions of absorption under...
A Schottky-contact triangular-barrier optoelectronic switch (STOS), grown by molecular beam epitaxy (MBE), has been fabricated. The triangular barrier, formed by inserting an InGaAs delta-doped (delta-doped) quantum well into an n -GaAs layer, provides a potential well for hole accumulation. Due to the hole accumulation in the delta-doped well and the sequential avalanche multiplications in the reverse-biased...
Transport properties of multiple electron species in two samples of indium nitride (InN) grown by molecular beam epitaxy (MBE) have been measured. Variable field Hall and resisitivity data were used in a quantitative mobility spectrum analysis (QMSA) to extract the concentrations and mobilities of two electron species, attributed to the bulk and a surface accumulation layer. While the properties of...
Femtosecond two-color spectrally-resolved nonlinear spectroscopy is used to study the dynamics of excited carriers in Si quantum dot structures embedded in SiN. Ultrashort population relaxation times of < 400 fs and ~ 6-10 ps are measured and discussed in the context of the different contributions from zero-phonon and transverse optical and transverse acoustic phonon-assisted transitions.
In this contribution, we implement a self-consistent procedure for the solution of the Poisson-Schrodinger model applied here for the analysis of coupled effects in wide bandgap wurtzite heterostructures. Such effects are demonstrated on examples for three-layer systems, in particular AlN/GaN quantum well heterojunctions, which are promising components in a number of optoelectronic device applications...
Based on DSCM (digital speckle correlation method), a novel video control experimental technique was developed for assessing mechanical behavior of SnAgCu solder alloy. A series of experimental tests in tension on a SnAgCu solder alloy have been conducted under various constant strain rates ranging from 10E-5/s to 10E-3/s and at 298K to 423K. The experimental results have revealed the presence of...
This study presents the theoretical design and analysis of a new surface micro-machined tuneable Fabry-Perot (FP) infrared filter for adaptive infrared photon detectors. The proposed structure uses broad spectral range, high reflectivity distributed Bragg reflector (DBR) mirrors based on amorphous Si/air layers, resulting in very high finesse filters. The device utilises three sacrificial layers to...
We analyze resonant transmission in photonic-crystal waveguides coupled to nonlinear resonators. We reveal that the discrete nature of the photonic-crystal structures allows for a novel, geometry-mediated enhancement of nonlinear effects, based on the high-Q side-coupled nonlinear resonators, which can be useful for a design of all-optical slow-light photonic devices.
Developments in measurement equipment bandwidth and memory have allowed standard chaotic time series analysis of the multi-GHz output power fluctuations of a semiconductor laser operating chaotically. An investigation into the effect of noise shows the degradation of this analysis at low signal-to-noise ratios.
The characteristics and device mechanism of InP/InGaAs pnp δ-doped heterojunction bipolar transistor are demonstrated. The additions of a δ-doped sheet and two spacer layers efficiently eliminate the potential spike at emitter-base junction, lower the emitter-collector offset voltage, and increase the confinement effect for electrons, simultaneously. The components of base current and the influence...
We report a two-temperature procedure for the growth of GaAs nanowires by metalorganic chemical vapour deposition. An initial high temperature step affords effective nucleation and promotes epitaxial growth of straight (111)B-oriented nanowires. Lower temperatures are employed subsequently, to minimise nanowire tapering during growth.
Porous silicon has many properties useful for optics applications, which include an ability to produce thin films with a wide range of refractive indices and the ability to easily fabricate multilayer structures. However porous silicon does have some non-optimal properties due to the very nature of its porous structure, namely its large surface area. The porous silicon surface is quite reactive making...
This study discusses a technique to define the reliability and predict the lifetime of NMOS transistor through stressing and analyzing process by using Agilent 4070 Series equipment and xHCI software at wafer level. The stressing process uses direct current stressing method while Takeda and Hu models are used in analysis process. The result of the experiment is in the graph form and it depends on...
Photonic crystal and photonic wire structures are being produced using a variety of techniques and form a challenging area of research activity. Metamaterials for the optical frequency range are extending what is physically possible and helping to push the boundaries of nanophotonics.
We present first results on heteroepitaxy of InP on silicon on insulator (SOI). We also demonstrate InP nanopillar fabrication by means of selective epitaxy. Selective epitaxy is also exploited to fabricate advanced photonic integrated devices for optical code division multiplex access (OCDMA) networking applications.
Operation of many electrostatically-activated MEMS devices, such as signal processors and inertia! sensors, is reliant on the on-chip availability of large DC voltage (>50 V). Although, voltage multipliers are suitable structures for achieving high DC voltages, the reduced junction breakdown-voltage of today's CMOS technology and body-effect complications restrict the maximum output voltage of...
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