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Spin relaxation under identical Dresslhaus and Rashba coupling in GaAs quantum wells is studied in both the traditional collinear statistics. It is shown that there is only marginal difference between the spin relaxation times obtained from these two different statistics.

Pseudomorphic four-period GaAs0.978N0.022/GaAs0.78Sb0.22 type-II multi-quantum well structures were grown on (100) GaAs substrates by metalorganic vapor phase epitaxy (MOVPE). Photoluminescence (PL) peak energies were obtained from GaAsN/GaAsSb type-II superlattive structures grown by MOVPE.

The carrier transfer between quantum dot (QD) and quantum well (QW) layers is analyzed in a hybrid dot-well system based on InAs QDs and InGaAs QWs. Strong state-filling effects of the excited QD states have affected the carrier transfer efficiencies.

An epitaxied AlGaAs/GaAs/AlGaAs heterostructure is analyzed by using the low frequency noise technique over a wide range of temperature as function of bias. Thermal activation energies and capture cross sections of traps responsible for the generation-recombination noise are extracted from an Arrhenius plot.

A new optoelectronic measurement of quantum well (QW) thickness is described and it is applied to doped and undoped [In.sub.0.53][Ga.sub.0.47]As/[In.sub.0.52][Al.sub.0.48]As multiple-QW structures. The QW thicknesses have agreed well with the QW thicknesses estimated by double-crystal x-ray diffraction within almost two monolayers, which are used for determining the distance of potential boundaries confining the electron wave functions.

The effect of a nonsharp and disordered potential in quantum well infrared photodetectors (QWIP is studied. The studies have shown that QWIP properties are very robust with regard to the nonideality of the energy band profile.

The article discusses a newly developed Aharonov-Bohm (AB) system, which is completely based on the various electron-hole bilayer nanotubes made of rolled-up type-II band aligned quantum wells. These nanotubes are shown to be widely used for a large number of magneto-optical switching devices and similar applications.

Several measurements are conducted to explain the various intersubband absorptions taking place in the p-doped GaAs/AlGaAs quantum well structures. The analysis is shown to be extremely beneficial for the designing of different emitters and detectors based on such systems.

Microdisk and microstadium resonators based on InGaAsP multiquantum-well laser structures are prepared by focused ion beam by using [Ga.sup.+] ion milling and polishing followed by selective chemical etching. The mode selection dependence with the surrounding index of refraction is described for chemical sensing applications.

The magnetotransport properties of a gated [In.sub.0.53][Ga.sub.0.47]As/InP quantum well structure are studied in the presence of spin splitting when only one electronic subband is occupied. The studies have shown that larger quantum mobility is found for the higher-energy spin subband and the difference between the quantum mobilities for the two spin subbands is altered with the gate.

A numerical study is performed on the linewidth enhancement factor ([alpha]-parameter) in single and multiple-quantum-well structures built from [In.sub.0.38][Ga.sub.0.62][As.sub.1-y][N.sub.y]/GaAs material systems. The studies have shown that engineering the desired linewidth enhancement factor is possible by varying the parameters.

The properties of an exciton bound to a neutral donor ([D.sup.0],X) in a parabolic GaAs quantum-well wire in the presence of a parallel magnetic field are examined by using the finite-difference method within the quasi-one-dimensional effective potential model. The results have shown that high magnetic fields have increased the binding energy of the [D.sup.0],X in the case of weak spatial confinement.

The properties of ionized-donor-bound excitons in a parabolic quantum-well wire in the presence of a magnetic field are analyzed in the framework of effective-mass envelope function theory. The results have shown that the binding energy has increased as the oscillator length has decreased and that it is also enhanced by increasing the magnetic field.

The temperature-dependent surface photovoltage spectroscopy (SPS) technique is employed to explain the characterization of the highly strained InGaAs/GaAs double quantum well (DQW) structures. The band lineup and several other properties of the structures are also analyzed.

The article uses electron temperature model to study the energy loss rate of hot electrons in a semiconducting freestanding quantum well structure, in the presence of zero and finite quantizing magnetic field. Findings are evaluated to those obtained for bulk description of acoustic phonon modes.

The temperature dependence of excitonic properties for an InGaAs/GaAs p-i-n multiquantum well structure grown on a (111)B GaAs substrate by molecular-beam epitaxy is studied by using photoreflectance spectroscopy, in which the pyroelectric effect is considered. The optical-phonon energy and strength of electron-phonon coupling for the crystallographic directions of the material system, as well as the interface roughness from an analysis of the temperature dependence of PR broadening parameters are determined.

A detailed study of double barrier strained [Al.sub.0.35][Ga.sub.0.65]As/AlAs/GaAs/[In.sub.0.2][Ga.sub.0.8]As quantum well infrared photodetectors on GaAs substrate, is presented. The experimental results demonstrated the impact ionization as the restrictive transport process for midwave detectors in the background limited regime.

Microscopic theory in combination with a band structure calculation based on ten-band k*p theory specially formulated for highly strained materials are employed to explore the material properties of highly strained GaInNAs quantum wells grown on GaInAs or quasi-GaInAs substrates. The application of the lasers for high-temperature and high-speed operation is demonstrated based on the very high temperature [T.sub.0] and differential gain with moderate strain which are achieved by carefully designed quantum well structures.

A comprehensive study on the well-width dependence of in-plane optical anisotropy (IPOA) in (001) GaAs/[Al.sub.x][Ga.sub.1-x]As quantum wells induced by in-plane uniaxial strain and interface asymmetry is presented. The results from theoretical calculations provide insight into the different well-width dependence of IPOA induced by in-plane uniaxial strain and interface asymmetry.

Spatial nonlocal effects on optical absorption spectra from the terahertz optical interaction with semiconductor quantum wells (QWs) are examined for two types of polarized states. The studies have shown that the spatial nonlocality of optical responses can lead to not only the blueshift but also the redshift of optical spectral, which has depended on the QW depth.

InGaAsP quantum well (QW) structures are grown on an In[As.sub.0.21][P.sub.0.79] metamorphic substrate layer (MSL) deposited on an InP substrate. The samples with the MSL have displayed more intermixing either due to a higher diffusion or greater P-As exchange probability in the different composition QW and barrier layers when compared to the QW structure grown without the MSL and possibly influenced by the large reduction in phase separation.

Enhanced side-mode suppression in Bunimovich stadium lasers with strained InGaAs/InGaP quantum well (QW) active regions is described. The improvement in side-mode suppression is a consequence of coherent beating between orbits leading to a Vernier effect.

An optical study is used for analyzing the cuboidal single pillar microresonators with a quantum-dot-like emitter formed from local fluctuations in the InGaAs/GaAs quantum well potential. The quantum dot character of the lasing is confirmed in a temperature dependent experiment, which has indicated a number of emission intensity oscillations.

A study is conducted to compare the structure and the photoluminescence (PL) properties of [In.sub.0.2][Ga.sub.0.8]As/GaAs quantum well (QW) structures grown on (311)-oriented substrates and the band gap temperature dependence of bulk [In.sub.0.2][Ga.sub.0.8]As. The sharp difference observed for the QW-exciton temperature from the band gap temperature dependence of bulk [In.sub.0.2][Ga.sub.0.8]As is attributed to temperature and well width dependent modification of the QW energy levels by the Stark effect.

A new method is developed for achieving the functionality of a double-sided mask aligner by using a much less expensive and more commonly available single-sided aligner. The alignment method and wafer design simulation procedure are applicable to a wide range of semiconductor devices.

The studies related to the thermally induced tensile and compressive strain on bulk GaAs and GaAs/AlGaAs multiple quantum wells (MQWs) are presented. The results showed that the epitaxially lifted-off (ELO) technique could be used as a powerful tool to introduce strain in GaAs heterostructures and for strain related spectroscopic study.

The analysis of chemical changes determined from the quantitative comparison of intensity distribution across an interface in high resolution transmission electronic microscopy (HRTEM) images is described. Four different samples of InGaP/GaAs quantum wells grown with different interfacial schemes are characterized.

The effect of Rashba spin-orbit coupling for a series of two-dimensional electron gases in [In.sub.0.52][Ga.sub.0.48]As quantum wells, surrounded by [In.sub.0.52][Al.sub.0.48]As barriers, where either one or two electric subbands are populated is studied. The results are discussed with the consequences for spintronic devices operating on the principle of charge density dependent or electric field dependent spin manipulation in narrow band gap semiconductors.

The nanoscale InGaAs/InAlAs multi quantum well structures were used to analyze the nonparabolicity of the conduction band in [In.sub.0.53][Ga.sub.0.47]As. The results obtained from the method provide a direct means to determine the quantum well thickness.

A comprehensive study of the growth and fabrication of Bragg-spaced quantum well, a type of resonant photonic band gap structure is conducted. Results revealed that drift in the growth rate greater than a few percent leads to collapse of the resonant photonic band gap (RPBG), while random disorder of several percent leads to extra peaks in the RPBG due to coupling to the intermediate band.

The variations of the optical and electrical characteristics of a vertical cavity surface emitting laser based on GaAs quantum wells are monitored. The results allow deducing the equivalence between electron and proton irradiations.