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Excess noise and multiplication is measured on a systematic series of omega = 0.1 Mum A1xGa1-xAs-GaAs type A and B heterojunction p(super +) -i-n(super +) diodes with x = 0.3, 0.45, and 0.6. The noise characteristics of the heterojunction Avalanche photodiodes (APDs) were found to depend critically upon the injection conditions, with lowest noise corresponding to pure electron injection into a type A device for all values of x.

Electron and hole multiplication properties were measured to determine the role of band edge discontinuities on ionization rates in A1xGa1-xAs/GaAs structures.

Detailed investigations are conducted on the impact ionization in 1-2.5 mum thick AlxGa(sub 1-x)As/GaAs multiple quantum well (MQW) avalanche photodiodes with various barrier and well widths. Studies reveal that lower ionization coefficients of the AlxGa(sub 1-x)As results in behavior that is similar to that of a pseudoalloy of the wells and barriers.

Highlights a study which measured electron and hole initiated multiplication in a series of AlxGa1-xAs/GaAs heterostructures, to examine the involvement of impact ionization across a single heterojunction. Definition of heterojunctions; Structures of p+in+ diodes; Methodology used to conduct the study; Results of the study.

Abstract: Intermixing in InAs quantum dots (QDs) grown by molecular-beam epitaxy (MBE) and metal-organic chemical vapor deposition (MOCVD) techniques on GaAs and InP substrates have been investigated by rapid thermal annealing (RTA) and laser-irradiation techniques. In all cases, substantial energy shifts have been observed after RTA and laser annealing. A comparison between the intermixed QD and quantum well (QW) structures shows distinguished differences in photoluminescence (PL) intensity and full-width at half-maximum (FWHM). For QD structures, an increase in PL intensity and a reduction in FWHM were observed after intermixing, whereas for QW structures the FWHM increased and the PL intensity reduced after intermixing, suggesting degradation of the material quality in the QWs after intermixing. Examination of the role of the surrounding matrix in intermixing process shows that InAs QDs placed in a InGaAs QW can retain its good optical quality after high temperature annealing, as the InGaAs QW provides a foundation for the QDs to be fully desorbed in the well. [Copyright &y& Elsevier]

Characterizes the electron multiplication of thin aluminum gallium arsenide/gallium arsenide heterostructures. Influence of the electric fields on the multiplication behavior; Enhancement of electronic ionization in heterostructures; Comparison of heterostructures with different aluminum compositions.

In this article, using an in situ micro-structured buffer, we report the growth of high-quality InAs epilayer on GaAs substrate by molecular beam epitaxy. Structural characterization of such InAs epilayer was carried out using cross-sectional transmission electron microscopy (TEM), X-ray diffraction (XRD), and depth-resolved channeling contrast microscopy (CCM). TEM and CCM images clearly show that the dislocations are trapped in the thin buffer layer between the InAs epilayer and the GaAs substrate interface. A narrow XRD peak from the InAs epilayer grown by this technique indicates good crystalline quality. In addition, the XRD peak position and the optical phonon peaks obtained from micro-Raman measurements confirm that the strain has been released in the InAs epilayer. [Copyright &y& Elsevier]