Electron-stimulated reduction of the surface of graphite oxide

Auger-electron spectroscopy has been used to study in situ the initial stage of graphite oxide (GO) reduction under the action of a low-intensity electron beam that does not lead to heating of the irradiated region. It was found that this stage evolves at a rate that is tens of times the rate of the subsequent reduction. It was shown that the fast stage is associated with the removal of oxygen groups from the GO surface. The effective cross sections of the initial and subsequent stages of GO reduction by 1500 eV electrons were found to be σ_in ~ 0.5 × 10^–16 cm² and σ_av ~ 1.2 × 10^–18 cm², respectively.     

Arsenic Diffusion in the Natural Oxidation of the Heavily Defected GaAs Surface

Semiconductors - Oxidation specific of the defected GaAs has been considered on the basis of elemental and chemical composition study of the oxide layer naturally emerged on the GaAs surface...     

Composition and Band Structure of the Native Oxide Nanolayer on the Ion Beam Treated Surface of the GaAs Wafer

Detailed information on GaAs oxide properties is important for solving the problem of passivating and dielectric layers in the GaAs-based electronics. The elemental and chemical compositions of the native oxide layer grown on the atomically clean surface of an n-GaAs (100) wafer etched by Ar⁺ ions have been studied by synchrotron-based photoelectron spectroscopy. It has been revealed that the oxide layer is essentially enriched in the Ga₂O₃ phase which is known to be a quite good dielectric as compared to As₂O₃. The gallium to arsenic ratio reaches the value as high as [Ga]/[As] = 1.5 in the course of oxidation. The Ga-enrichment occurs supposedly due to diffusion away of As released in preferential oxidation of Ga atoms. A band diagram was constructed for the native oxide nanolayer on the n-GaAs wafer. It has been shown that this natural nanostructure has features of a p–n heterojunction.     

Defect Formation under Nitrogen-Ion Implantation and Subsequent Annealing in GaAs Structures with an Uncovered Surface and a Surface Covered with an AlN Film

Semiconductors - The concentration profiles of defects produced in structures upon the implantation of nitrogen ions into GaAs epitaxial layers with an uncovered surface and that covered with an...     

The Effect of Dose of Nitrogen-Ion Implantation on the Concentration of Point Defects Introduced into GaAs Layers

Secondary-ion mass spectrometry and Rutherford proton backscattering have been used to measure the concentration profiles of nitrogen atoms and examine the defect structure of epitaxial GaAs layers implanted with 250-keV N⁺ ions at doses of 5 × 10¹⁴–5 × 10¹⁶ cm^–2. It was found that no amorphization of the layers being implanted occurs at doses exceeding the calculated amorphization threshold, a concentration of point defects that is formed is substantially lower than the calculated value, and a characteristic specific feature of the defect concentration profiles is the high defect concentration in the surface layer.     

Controlling graphite oxide bandgap width by reduction in hydrogen

Transformation of the chemical composition and electron structure of graphite oxide (GO) nanolayers as a result of their annealing in hydrogen has been studied by X-ray photoelectron spectroscopy using synchrotron radiation. It is established that both the chemical composition and bandgap width of GO can be controlled by varying the temperature and duration of heat treatment. By this means, the properties of GO nanolayers can be smoothly changed from dielectric to semiconductor.     

J–V Characteristic of p–n Structure Formed on n-GaAs Surface by Ar+ Ion Beam

Semiconductors - A highly defective ~10-nm-thick layer was fabricated in a high vacuum by 2.5 keV Ar+ ion bombardment of the n-GaAs surface. Valence band photoelectron spectra showed a p-type...     

Сomposition Depth Profiling of the GaAs Native Oxide Irradiated by an Ar+ Ion Beam

Semiconductors - The elemental and chemical compositions throughout the thickness of the GaAs native oxide layer slightly irradiated by Ar+ ions have been studied by synchrotron-based photoelectron...     

In situ Bandgap Determination of the GaAsN Nanolayer Prepared by Low-Energy $${\text{N}}_{2}^{ + }$$ Ion Implantation

Semiconductors - An approach to solving the problem of the in situ bandgap determination in the extremely thin and chemically active nitride nanolayers fabricated in high vacuum on the n-GaAs...     

Core electron level structure in C<Subscript>60</Subscript>F<Subscript>18</Subscript> and C<Subscript>60</Subscript>F<Subscript>36</Subscript> fluorinated fullerenes

The structure of C1s and F1s core electron levels in C₆₀F₁₈ and C₆₀F₃₆ fluorinated fullerenes has been studied by X-ray photoelectron spectroscopy using synchrotron radiation. It is established that C1s levels of carbon atoms not bound to fluorine in these compounds are shifted down by 1.0 and 1.6 eV relative to the C1s level in the usual C₆₀ fullerene, so that the binding energies of the core electron levels in C₆₀F₁₈ and C₆₀F₃₆ amount to E _b (C1s, C-C) = 285.7 and 286.3 eV, respectively. These values are characteristic and can be used for the identification of both homogeneous fluorinated fullerenes and combined materials comprising a mixture of various fluorinated fullerenes with each other and with different carbon-containing based materials.