Optical Analyses of Si and GaAs Semiconductors by Fractional-Derivative-Spectrum Methods

Optical spectra analysis provides a wealth of information on physical properties of various semiconductor materials. Fractional derivative spectrum technique is especially interesting when the limitations of the standard treatment occur. In this paper we present the fractional derivative spectrum method for analysis of the optical spectra for both Si and GaAs. The significant changes in critical point parameters in each treated Si and GaAs samples in comparison to that before treatment have been observed. Our investigation illustrates that fractional derivative spectrum is a very good technique to extract basic information on relevant physical quantities from the observed optical spectra, and it has the advantages of flexibility, directness, and sensitivity, which give possibility to obtain the Van Hove singularities (critical point parameters) efficiently with one consent

Dependence of Nanoelectronic-Structure Defect Detection by Cathodoluminescence on Electron Beam Current

The dependence of defect detection by cathodoluminescence in a scanning electron microscope on the electron beam current is considered. The examined specimens are AlGaAs/GaAs laser heterostructures with InGaAs quantum well. It is shown that for low electron beam currents, which are typically used, the uniform cathodoluminescence is observed, while for the increasing high electron beam current the oval defects become more and more visible. The influence of electrical properties of the structure on the luminescence detection is explained

Effect of Secondary Electroluminescence on Cathodoluminescence and Other Luminescence Measurements

Cathodoluminescence and photoluminescence measurements are commonly accepted as revealing local properties of a specimen region excited by a beam of electrons or photons. However, in the presence of a strong electric field (e.g. a junction) an electron (or light/laser) beam-induced current is generated, which spreads over the structure. A secondary non-local electroluminescence, generated by this current and detected together with the expected luminescence signal, may strongly distort measurement results. This was confirmed by cathodoluminescence measurements on test structures prepared by focused ion beam on AlGaAs/GaAs/InGaAs laser heterostructures. Methods for minimizing the distortion of measured luminescence signals are presented

The influence of MBE growth conditions on optical properties of InGlGaAs/AlGaAs structures

Optical properties of compressively strained In₀.₂₄Al₀.₁₉Ga₀.₅₇As layers were investigated as a function of the MBE growth conditions. The optimum temperature of the crystal surface (Ts) for MBE growth of this quaternary layer as well as the optimal cooling down process necessary for achieving appropriate Ts for InAlGaAs were experimentally found

Oval defects in crystals grown by MBE technique: study and methods of elimination abstract

The paper is devoted to a group of macroscopic defects which may be found in epitaxial A3 B5 materials grown by MBE technique. Morphology, geometry and optical properties of defects were studied by means of several experimental methods. The experimental data have been compared with the information taken from literature concerning sources of the defects and causes of their appearance

The Study of Thermal Properties of GaAs/AlGaAs Quantum Cascade Lasers

Temperature change in quantum cascade laser can be estimated by studying the device resistance change. Using this method we compared quantum cascade laser structure mounted on diamond heat spreader and without heat spreader. We have shown that the use of heat spreader reduces temperature increase even by 40%

Asymmetrically Shaped Pseudomorphic Modulation Doped Structure for Microwave Detection

In this paper we propose a microwave detector based on a AlGaAs/InGaAs/GaAs structure. Its operation relies on non-uniform carrier heating of the two-dimensional electron gas in the microwave electric fields which is a result of the asymmetric shape of the device fabricated on the base of pseudomorphic modulation doped AlGaAs/InGaAs/GaAs structure. The voltage sensitivity of the device at nitrogen temperature is 38 V/W for 10 GHz radiations and is higher compared to that of modulation doped AlGaAs/GaAs of the same configuration