The effect of fast neutrons on the conductance of single-crystal silicon

The dependence of variation of the specific conductance of single-crystal silicon on the fast neutron fluence is calculated. The results of calculations are compared with the experimental data obtained in two channels of an IRT-T reactor with different neutron spectra. These experimental data are also discussed. The fast neutron fluence was controlled using threshold sulfur activation detectors. The specific electrical resistance was measured by a 4-probe method. The calculation data are in good agreement with experiment and show that the variation of the specific conductance due to exposure to fast neutrons is in direct proportion to the fluence of these neutrons. The proportionality coefficient depends on the neutron spectrum, but is independent of the initial specific conductance. In so doing, it makes no difference, whether silicon was previously irradiated or not.     

Study of the formation of silicon nanoclusters in silicon dioxide during electron beam irradiation

Irradiation of silicon dioxide by an electron beam with a high specific power leads to the formation of silicon nanocrystals in the irradiated region and the formation of a modified region, i.e., a Si-SiO₂ nano-composite. This work is devoted to studying the formation of this nanocomposite and of its luminescence properties.     

Theoretical analysis of the impurity distribution in single-crystal silicon

Results are presented for the total energies calculated for oxygen and carbon impurities in silicon at T=0 K. The equilibrium positions of these point defects are determined at low (10⁻³–10⁻² at. %) concentrations. Fiz. Tverd. Tela (St. Petersburg) 39, 1384–1385 (August 1996)     

Laser induced single-crystal transition in polycrystalline silicon

Transition to single crystal of polycrystalline Si material underlying a Si crystal substrate of 〈100〉 orientation was obtained via laser irradiation. The changes in the structure were analyzed by reflection high energy electron diffraction and by channeling effect technique using 2.0 MeV He Rutherford scattering. The power density required to induce the transition in a 4500 ? thick polycrystalline layer is about 70 MW/cm² (50ns). The corresponding amorphous to single transition has a threshold of about 45 MW/cm².     

Internal friction measurements in Boron-doped single-crystal silicon

Internal friction measurements, Q^?1, of a boron-doped single crystal of silicon at a frequency ω = 2π × 29.2 kHz showed: (1) results in agreement with the Akhieser mechanism above 100 K; and (2) Q^-1 ∝ ωT^?1 at temperatures below 10 K.     

Role of electron confinement in the formation of Tamm surface levels in nanoparticles

We study the effect of electron confinement in a nanoparticle on the parameters of Tamm’s levels. It is shown using the combination of the Tamm model and the Kronig-Penney model that an increase in the gap width in the electron spectrum of the crystal leads to an increase in the energy of the Tamm state and a decrease in the degree of localization of the wavefunction of the Tamm state. Some applications of the results on the properties of the Tamm level (e.g., the effect on the surface tension of a nanocluster, the manifestation of modifications considered here in the multiple exciton generation effect in quantum dots, the possible role of the shape of a nanoparticle during its growth, and the role of varying Tamm states in catalysis by nanoparticles) are indicated.     

Spectromicroscopic study of plasma-treatment effect on InP-substrate-based silicon nitride and silicon oxide patterns

Oxygen-plasma treatment was applied to silicon nitride and silicon oxide patterns on an InP substrate, and the effect was investigated by using scanning photoelectron microscopy. After the plasma treatment, the relative intensity of the carbon content was noticeably reduced on the surfaces of the patterns and the substrate, which indicates that the plasma treatment effectively removed the remaining carbon and made the patterns more resistant to carbon contamination. The oxygen-plasma treatment formed a thick oxidized surface on the InP substrate, which results in less occurrence of carbon contamination . PACS 68.37.Xy; 52.77.Bn; 85.40.-e     

Spectrum broadening effect in coherent x-ray radiation of a relativistic electron crossing a single-crystal plate

Based on the dynamic diffraction theory [1], coherent x-ray radiation of a relativistic electron crossing a single-crystal plate at a constant velocity is considered in the Bragg geometry. In the general case of asymmetric reflection of the radiation from the target, expressions are derived for the spectral-angular distribution of parametric x-ray radiation (PXR) and diffraction transition radiation (DTR). For a fixed angle between the electron trajectory and the system of parallel atomic planes of the crystal (Bragg’s angle) it is shown that a decrease in the angle of electron incidence on the crystal plate gives rise to a significant increase in the PXR and DTR spectra, and the causes for spectral broadening for each of these radiation mechanisms are different. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 74–83, March, 2009.     

Simultaneous presence of unindexed lines with different signs of contrast in Kikuchi patterns

We have obtained Kikuchi patterns of silicon. The patterns contain simultaneously bright and dark unindexed lines. Formation and the contrast of these Kikuchi lines are explained by the phenomenon of double diffraction of Kikuchi electrons. Conclusion is drawn that the sign of contrast of unindexed Kikuchi lines does not depend on the thickness of a crystal.     

Role of masking oxide on the silicon surface on defect formation in SIMOX structures

The properties of Si/SiO₂ structures produced by oxygen implantation into silicon (SIMOX technology) are investigated by the high-frequency C-V method and by the electroluminescence (EL) method. The existence of electrically active and luminescence centers in the oxide layer near the interface is established. The effect of a SiO₂ masking layer on the silicon surface on defect formation in the SIMOX structure is elucidated. The dependence of the concentration of the electrically active and luminescence centers on the thickness of the masking layer is found.     

Formation of ultrathin iron silicide layers on the single-crystal silicon surface

The solid-phase synthesis of iron silicides on the Si(100)2 × 1 surface with a 5-ML-thick iron film deposited at room temperature was studied by high-resolution photoelectron spectroscopy with the use of synchrotron radiation. Computer simulation of the measured Si 2p spectra revealed the formation of silicides in this system already under annealing at a temperature of 60°C. The process of formation consists in successive syntheses of three iron silicide phases, more specifically, monosilicide ε-FeSi, metastable disilicide γ-FeSi₂, and disilicide β-FeSi₂. The temperature ranges of existence of these phases were determined. Silicon was found to segregate on the γ-FeSi₂ surface.     

The effect of channeling on MeV ion-induced auger electron production in silicon

We have measured Auger electron emission from single crystal targets of Si(111) bombarded with H⁺ and ⁴He⁺ beams in the 0.5 to 1.8 MeV range under channeled and random directions of incidence. Under channeling conditions (monitored by simultaneous measurement of the Rutherford backscattering yield), a significant reduction is observed in the intensity and also in the energy width of the KLL Auger line. These two characteristics of the Auger signal are influenced by channeling of the incident beam as evidenced by their angular dependence. The measured ratio of the channeled to random Auger signals correlates well with a simple model based on the shadow cone radius for the channeled ion, the lattice vibrational amplitude, the adiabatic K-shell excitation distance, and the electron inelastic mean free path, λ, for the 1620 eV Auger line. We derive a value for the latter quantity of 34 Å.