Influence of the preparation conditions on the size and morphology of nanocrystalline lanthanum orthoferrite

Nanocrystalline LaFeO₃ is prepared by the dehydration of coprecipitated lanthanum and iron(III) hydroxides. It is shown that the behavior of the samples during heating and the size distribution of LaFeO₃ nanocrystals can be considerably different depending on the scheme used for coprecipitation of lanthanum and iron hydroxides; independently of the method employed for coprecipitation of the initial compounds, sintering of the samples at 950°C leads to the formation of lanthanum orthoferrite crystals up to 100 nm in size.     

Effect of Oxidizers on the Growth of Indium Oxide Films from Indium Acetylacetonate Vapor

The introduction of oxidizers (O₂, N₂O, N₂O + O₂ mixture) into the gas phase (argon) affects the growth rate, composition, and properties of the films prepared via thermal decomposition of indium acetylacetonate, In(acac)₃. N₂O increases the average growth rate of the films by a factor of 3. It was proved by the radical fixation method that N₂O oxidizes In(acac)₃ molecules chemisorbed on the substrate, thus changing the composition and improving the electrical properties of the films.     

Synthesis and catalytic performance of V<Subscript>2</Subscript>O<Subscript>5</Subscript> nanoislands produced on the surface of InP crystals by electroexplosion

We report the deposition of chemostimulator nanoislands on the surface of indium phosphide by an electroexplosion process and the effect of experimental conditions (ambient composition, pressure, and source-substrate distance) on their size distribution and surface density. Vanadium oxide and vanadium islands are shown to have a catalytic effect on the surface oxidation of indium phosphide, ensuring one of the most effective interactions between a chemostimulator and a III–V semiconductor in an oxidizing atmosphere.     

Kinetics of the nanocrystal formation in the ZrO<Subscript>2</Subscript>-In<Subscript>2</Subscript>O<Subscript>3</Subscript>-H<Subscript>2</Subscript>O system under hydrothermal conditions

The hydrothermal synthesis of nanocrystals in the ZrO₂-In₂O₃-H₂O system is investigated kinetically. The presence of indium hydroxide results in an increase in the dehydration temperature of this system. The size of nanocrystals is equal to 20–30 nm and virtually does not depend on the temperature and time of hydrothermal treatment or on the type of crystalline modification of ZrO₂. An increase in the synthesis temperature leads to an increase in the fraction of the monoclinic zirconia modification.Original Russian Text Copyright © 2005 by Fizika i Khimiya Stekla, Artamonova, Almjasheva, Mittova, Lavrushina, Gusarov.     

Thermal oxidation of V2S5/InP heterostructures in oxygen

X-ray emission and IR spectroscopy data are used to elucidate the mechanism of thermal oxidation of V₂S₅/InP structures in oxygen. The substrate-activator interaction is shown to have a significant effect on the oxidation mechanism and to improve the engineering performance of the structures.     

GaAs Thermal Oxidation by Introducing CrO3 into a Gaseous Oxidizer

It is shown that the introduction of chromium(VI) oxide into a gaseous oxidative atmosphere leads to a complex activation mechanism of GaAs oxidation. This mechanism involves processes taking place largely in the activator itself. The kinetics of oxidation in dry and wet media, as well as the catalytic action of various chemistimulator phases, were studied. It was found that good insulating layers can be obtained when thermal oxidation proceeds in the presence of the chromium oxides.     

Effect of V<Subscript>2</Subscript>O<Subscript>5</Subscript> nanoislands on the surface composition and structure of InP during thermal oxidation

The evolution of the surface morphology and composition during the thermal oxidation of InP in the presence of V₂O₅ nanoislands has been studied by scanning tunneling microscopy and Auger electron spectroscopy. The results demonstrate that the effect of the islands is strongest in the initial stage of the process and persists in later stages. Auger electron spectroscopy and kinetic data strongly suggest that the oxidation of InP in the presence of vanadium oxide nanoislands follows a catalytic mechanism.     

Solid-Phase Reactions in the Thermal Oxidation of Ni/GaAs Heterostructures

The thermal oxidation of GaAs covered with an Ni layer is studied experimentally. It is shown that this layer makes for better dielectric performance of the oxide film and inhibits the escape of the volatiles from GaAs. A possible pattern of the oxidation of Ni/GaAs heterostructures is put forward. It includes the formation of a transition layer between NiO and GaAs, which contains nickel–arsenic and nickel–gallium compounds. Reactions at the interface between the transition layer and NiO are considered.     

Thermal Oxidation of GaAs and InP in the Presence of Al2(SO4)3

The thermal oxidation of GaAs and InP is investigated when Al₂(SO₄)₃ is introduced into the oxidizing atmosphere. It is found that the stimulator accelerates the reaction in both cases. The process and films are examined by laser ellipsometry, IR spectroscopy, and XRF. On this basis the role is identified of the stimulator anionic component, which causes the oxidation to branch and increases its rate.     

Oxidation of vanadium films on InP substrates

The kinetics and mechanism of the thermal oxidation of V/InP structures in flowing oxygen are investigated by x-ray diffraction and IR spectroscopy. The results demonstrate that the oxidation of thin (25 nm) vanadium films yields various oxides, which accelerate the oxidation of indium phosphide, leading to the formation of multiphase dielectric layers through a number of parallel reactions.Translated from Neorganicheskie Materialy, Vol. 41, No. 3, 2005, pp. 263–267.Original Russian Text Copyright © 2005 by Mittova, Tomina, Lapenko.This revised version was published online in April 2005 with a corrected cover date.This revised version was published online in April 2005 with a corrected cover date.