Specific features of the sol-gel formation and optical properties of 3d metal/porous silicon composites

The composition and optical properties of composite materials based on porous silicon with iron, cobalt, and nickel deposited by the sol-gel technique are studied. It is shown that the deposition of metal-oxide films onto the surface of porous silicon enables stabilization of the photoluminescence and an increase in its intensity, as well as the storage of hydrogen in the porous layer.     

Structure and optical properties of heterostructures based on MOCVD (Al x Ga1 − x As1 − y P y )1 − z Si z alloys

Epitaxial heterostructures produced by MOCVD on the basis of Al _x Ga_{1 ? x} As ternary alloys with the composition parameter x ≈ 0.20–0.50 and doped to a high Si and P atomic content are studied. Using the high-resolution X-ray diffraction technique, scanning electron microscopy, X-ray microanalysis, Raman spectroscopy, and photoluminescence spectroscopy, it is shown that the epitaxial films grown by MOCVD are formed of five-component (Al _x Ga_{1 ? x} As_{1 ? y} P _y )_{1 ? z} Si _z alloys.     

Effect of Misorientation and Preliminary Etching of the Substrate on the Structural and Optical Properties of Integrated GaAs/Si(100) Heterostructures Produced by Vapor Phase Epitaxy

It is shown for the first time that the structural and optical functional characteristics of integrated GaAs/Si(100) heterostructures can be controlled by using misoriented Si(100) substrates and their preliminary etching. The growth of an epitaxial GaAs layer on a Si substrate without the formation of antiphase domains can be carried out on a substrate deviated from the (100) singular plane by an angle smaller than 4°–6° or without a transition layer of GaAs nanocolumns. Preliminary treatment of the silicon substrate by etching makes it possible to use it for the vapor-phase epitaxial growth of a single-crystal GaAs film with a considerably smaller relaxation coefficient, which has a positive effect on the structural quality of the film. These data are in good agreement with the results of IR reflectance spectroscopy and photoluminescence and ultraviolet spectroscopy. The features of the optical properties of integrated GaAs/Si(100) heterostructures in the infrared and ultraviolet spectral regions are also defined by the relaxation coefficient.     

Structural and spectral features of MOCVD Al x Ga y In1 ? x ? y As z P1 ? z /GaAs (100) alloys

The study is concerned with MOCVD epitaxial heterostructures grown on the basis of Al _x Ga _y In_{1 ? x ? y} As _z P_{1 ? z} quinary alloys in the region of alloy compositions isoperiodic to GaAs. By the X-ray diffraction technique and atomic force microscopy, it is shown that, on the surface of the heterostructures, there are nanometric objects capable of lining up along a certain direction. From calculations of the crystal lattice parameters with consideration for internal strains, it can be inferred that the new compound is a phase based on the Al _x Ga _y In_{1 ? x ? y} As _z P_{1 ? z} alloy.     

Study of the deposition features of the organic dye Rhodamine B on the porous surface of silicon with different pore sizes

The deposition features of the organic dye Rhodamine B on the porous surface of silicon with average pore sizes of 50–100 and 100–250 nm are studied. Features of the composition and optical properties of the obtained systems are studied using infrared and photoluminescence spectroscopy. It is found that Rhodamine-B adsorption on the surface of por-Si with various porosities is preferentially physical. The optimal technological parameters of its deposition are determined.     

Structural and optical properties of heavily doped Al x Ga1 − x As1 − y P y :Mg alloys produced by metal-organic chemical vapor deposition

The high-resolution X-ray diffraction technique, Raman spectroscopy, and photoluminescence spectroscopy are used to study the structural, optical, and electron energy properties of epitaxial Al _x Ga_{1 ? x} As_{1 ? y} P _y :Mg alloy films grown by metal-organic chemical vapor deposition (MOCVD). It is shown that the introduction of a Mg impurity into the quaternary alloy provides high charge-carrier concentrations. A decrease in the growth temperature yields a decrease in the charge-carrier concentration in films doped with magnesium at a small gas-carrier flux of the acceptor impurity, whereas an increase in the flux results in an increase in the acceptor-impurity concentration, which is reflected in the character of the photoluminescence spectra.     

Study of the morphological growth features and optical characteristics of multilayer porous silicon samples grown on n-type substrates with an epitaxially deposited p +-layer

This study is concerned with the growth features of multilayer porous silicon with layers of different porosity, obtained by electrochemical etching on an n-type single-crystal silicon (111) wafer with a p ⁺-layer epitaxially deposited onto the surface. The possibility of obtaining a multilayer system of ordered pores of various sizes within a single technological cycle is demonstrated. The differences in the optical characteristics of separate layers of the grown structure are shown.     

Growth features and spectroscopic structure investigations of nanoprofiled AlN films formed on misoriented GaAs substrates

Nanostructured aluminum-nitride films are formed by reactive ion-plasma sputtering onto GaAs substrates with different orientations. The properties of the films are studied via structural analysis, atomic force microscopy, and infrared and visible–ultraviolet spectroscopy. The aluminum-nitride films can have a refractive index in the range of 1.6–4.0 at a wavelength of ~250 nm and an optical band gap of ~5 eV. It is shown that the morphology, surface composition, and optical characteristics of AlN/GaAs heterophase systems can be controlled using misoriented GaAs substrates.     

Experimental studies of the effects of atomic ordering in epitaxial Ga<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>In<Subscript>1 – <Emphasis Type="Italic">x</Emphasis></Subscript>P alloys on their optical properties

The properties of epitaxial Ga _x In_{1 – x} P alloys with an ordered arrangement of atoms in the crystal lattice are studied by a number of spectroscopic methods. The alloys are grown by metal-organic chemical vapor deposition onto single-crystal GaAs(100) substrates. It is shown that, under conditions of the coherent growth of an ordered Ga _x In_{1 – x} P alloy on a GaAs(100) substrate, atomic ordering results in radical modifications of the optical properties of the semiconductor compared to the properties of disordered alloys. Among these modifications are a decrease in the band gap and an increase in the luminescence intensity. From the data of dispersion analysis of the infrared dispersion spectra and from ultraviolet spectroscopy data obtained in the transmittance–reflection mode of measurements, the basic optical characteristics, specifically, the dispersion of the refractive index and the high-frequency permittivity of Ga _x In_{1 – x} P alloys with ordering are determined. All of the experimental data are in good agreement with the developed theoretical concepts.