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In this work, different dielectric caps were deposited on the GaAs/AlGaAs quantum well (QW) structures followed by rapid thermal annealing to generate different degrees of interdiffusion. Deposition of a layer of Ga[sub x]O[sub y] on top of these dielectric caps resulted in significant suppression of interdiffusion. In these samples, it was found that although the deposition of Ga[sub x]O[sub y] and subsequent annealing caused additional injection of Ga into the SiO[sub 2] layer, Ga atoms were still able to outdiffuse from the GaAs QW structure during annealing, to generate excess Ga vacancies. The suppression of interdiffusion with the presence of Ga vacancies was explained by the thermal stress effect which suppressed Ga vacancy diffusion during annealing. It suggests that Ga[sub x]O[sub y] may therefore be used as a mask material in conjunction with other dielectric capping layers in order to control and selectively achieve impurity-free vacancy disordering. [ABSTRACT FROM AUTHOR]

Focuses on a study that used proton irradiation with subsequent rapid thermal annealing to investigate intermixing of InGaAs/GaAs and InGaAs/AlGaAs quantum wells. Experimental details; Results and discussion; Conclusions.

Focuses on a gallium-arsenide/aluminum arsenide (AlAs) multiple quantum well structure doped n-type in the AlAs barriers. Application of photoluminescence and Raman scattering; Summary of the magnetoluminescence results; Cause of the reduction of the energy gap.

Presents a study on a type of semiconductor quantum well system in which the carrier-ion exchange interactions are determined by the spin of the carrier. Effect of magnetic fields on excitonic wave functions in the study; Behavior of the spin-down component; Use of magnetoreflectance and photoluminescence to examine the behavior of heavy-hole excitons.

A bound-to-continuum quantum well solar cell structure is proposed, and the band structure and absorption spectra are analyzed by the use of an eight band k·p model. The structure is based on quantum wells that only support bound states for the valence band. The absence of bound conduction band states has a number of potential advantages, including a reduction of electron trapping and, therefore, a reduction of quantum well induced photocarrier recombination due to reduced spatial overlap of the electron and hole wavefunctions. [ABSTRACT FROM AUTHOR]

We investigate the quantum phase transition (QPT) and dynamics induced by atom-pair tunnelling of Bose-Einstein condensates in a symmetric double well under the mean-field approximation. We find the system undergoes a new QPT towards phase-locking state when atom-pair tunnelling is strong enough, and the critical point of self-trapping QPT is shifted by atom-pair tunnelling. As for the dynamics, the system displays localized dynamical behaviour: phase-locking motion and self-trapping motion. We further study the correlation between this localized dynamics and QPT, and find that the area of the localized trajectories in the phase space can serve as an order parameter for both QPTs. The critical exponent of this order parameter is also discussed. [ABSTRACT FROM AUTHOR]

The article investigates and compares two of the most important intermixing techniques, ion implantation and impurity free vacancy disordering, in InGaAs/(Al)GaAs quantum well (QW) and quantum dot (QD) structures. For ion implantation induced intermixing, arsenic implantation has been performed and the amount of interdiffusion created has been found to vary as a function of implantation dose and temperature. Impurity free vacancy disordering has also been enhanced by deposition of SiO2 in both QW and QD structures and annealing at different temperatures. In order to obtain large differential energy shifts for device integration using both methods, the essential issue of suppression of thermal interdiffusion using a TiO2 capping layer has also been addressed.

We report on the effects of the quantum well (QW) thickness on the spectral response and other characteristics of In0.5Ga0.5As/GaAs/Al0.2Ga0.8As quantum dots-in-a-well infrared photodetectors grown by low-pressure metal-organic chemical vapor deposition. The main device properties are observed to have a strong dependence on the QW parameters. [ABSTRACT FROM AUTHOR]

We report on the spectral behavior of two different quantum dots-in-a-well infrared photodetectors grown by low-pressure metal-organic chemical vapor deposition. In0.5Ga0.5As quantum dots embedded in an In0.15Ga0.85As/GaAs quantum well (QW) or a GaAs/Al0.2Ga0.8As QW have been incorporated into photodetectors and were characterized. A spectral response in the 3–5 μm atmospheric window has been achieved by adopting the GaAs/Al0.2Ga0.8As QW. [ABSTRACT FROM AUTHOR]

The effects of thermal annealing on C-doped InGaAs/AlGaAs quantum well laser structures capped with titanium dioxide (TiO2) layers were investigated. The atomic interdiffusion was greatly suppressed by the presence of a TiO2 capping layer during annealing, inhibiting even the thermal intermixing observed in the uncapped sample. An increase in the amount of lattice contraction associated with the presence of substitutional carbon CAs after annealing without a capping layer was observed, but not after annealing with a TiO2 capping layer. Capacitance–voltage measurements confirmed the electrical activation of carbon after annealing without a dielectric layer and show a negligible change after annealing using a TiO2 capping layer. The possible mechanisms involving both the atomic intermixing on the group III sublattice and carbon activation on the group V sublattice and the implications for optoelectronic device integration using impurity-free intermixing are discussed. [ABSTRACT FROM AUTHOR]

The effect of two different dopants, P and Ga, in spin-on glass (SOG) films on impurity-free vacancy disordering (IFVD) in GaAs/A1GaAs quantum-well structures has been investigated. It is observed that by varying the annealing and baking temperatures, P-doped SOG films created a similar amount of intermixing as the undoped SOG films. This is different from the results of other studies of P-doped SiO[SUB 2] and is ascribed to the low doping concentration of P, indicating that the doping concentration of P in the SiO[SUB 2] layer is one of the key parameters that may control intermixing. On the other hand, for all the samples encapsulated with Ga-doped SOG layers, significant suppression of the intermixing was observed, making them very promising candidates with which to achieve the selective-area defect engineering that is required for any successful application of IFVD. [ABSTRACT FROM AUTHOR]

Single high-energy (0.9 MeV) proton implantation and rapid thermal annealing was used to tune the spectral response of the quantum-well infrared photodetectors (QWIPs). In addition to the large redshift of the QWIPs' response wavelength after implantation, either narrowed or broadened spectrum was obtained at different interdiffusion extent. In general, the overall device performance for the low-dose implantation was not significantly degraded. In comparison with the other implantation schemes, this single high-energy implantation is the most effective and simple technique in tuning the wavelength of QWIPs, thus, to achieve the fabrication of multicolor detectors. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The quality of spin-on silica films prebaked at different temperatures has been studied using Fourier transform infrared spectroscopy, spectroscopic ellipsometry, and P-etch [HF(40%):HNO[sub 3](70%):H[sub 2]O=3:2:60] measurements. Low-temperature photoluminescence (PL) was performed on GaAs/AlGaAs quantum-well (QW) structures encapsulated by the same films. For all the prebaked films, not only the Si-O-Si peaks, but also OH-related peaks were detected in the IR spectra. After annealing at 950 °C for 60 s, almost all OH-related peaks disappeared. Spectroscopic ellipsometry modeling and P-etch measurements showed that the porosity of high-temperature (>300 °C) baked samples was similar, and was significantly higher than the low-temperature (210 °C) baked sample. The same trend was observed in the PL energy shifts from the GaAs/AlGaAs QWs, indicating a direct correlation between the film quality and quantum-well intermixing. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We have used photoluminescence up conversion to study the carrier capture times into intermixed InGaAs/GaAs quantum wells. We have found that the capture into the intermixed wells is markedly faster than capture into the reference (unintermixed) quantum wells. The reasons for the significant reduction in the capture time is related to the shape of the intermixed quantum well. Such a reduction in the capture time is beneficial both in terms of the quantum efficiency and the frequency response of intermixed optoelectronic devices. © 1998 American Institute of Physics. [ABSTRACT FROM AUTHOR]