Papers by Author: V.G. Litovchenko

Abstract: Ultra-shallow junctions (USJs) were formed by low-energy As ion implantation with the subsequent furnace annealing. It was found that the significant amount of oxygen is redistributed from the silicon bulk to the arsenic-implanted region. We present the effect of oxygen gettering at the creation of arsenic-doped USJs using the marker layer created by ion implantation of ¹⁸O isotope.

Abstract: The peculiarities of a buried layer formation obtained by a co-implantation of O2 ions with the energy of 130 keV and carbon ions within the energy range of 30-50 keV have been investigated. The corresponding ion doses for carbon and oxygen ions were equal to 2∙1016 cm-2 and 1.8∙1017 cm-2, respectively. It has been observed that annealing at 1150°C results in enhanced oxygen diffusion towards the region with a maximum carbon concentration. Analysis of x-ray diffraction patterns and TEM images confirm formation of Si nanoclusters in the SiO2 buried layer. The intensive luminescence with the maximum at 600 nm has been observed in the synthesized structures.

Abstract: In this paper, the influence of the gettering treatment on the distribution of diffusion length of minority charge carriers in multicrystalline silicon has been investigated. For the calculation of the parameters of diffusion length distribution, a new method has been proposed based on the mathematical treatment of experimentally measured integrated spectra of surface photovoltage measured by capacitor method (capacitor photovoltage). Obtained results show not only the increase of the average diffusion length as a result of used gettering procedure, but also the decrease of inhomogeneity of its distribution.

Abstract: In this paper, the influence of the rapid thermal annealing of single crystalline Cz-Si wafers on the evolution of the concentration of interstitial oxygen as well as oxygen in precipitated oxide phase was investigated by infrared spectroscopy. The wafers were preliminary furnace annealed to create the precipitate seeds. The concentration of interstitial oxygen was shows to decrease considerably as a result of annealing during up to 40 min together with the growth of the concentration of precipitated oxygen. This effect depended on the purity and defect structure of initial wafers. The kinetic model was developed to account for the observed effects based on the modification of the solubility level for interstitial oxygen induced by defects as well as its diffusivity. Obtained results of simulation agree well with the experimental data.

Abstract: IR-spectroscopy with computer analysis of the shape of the Si-O absorption band, electron microscopy, X-rays diffraction and measurements of unsteady photoconductivity timedecay under band-to band excitation were used to investigate the influence of defects in different diameter (40 – 300 mm) Si ingots on the oxygen precipitation due to two-stage annealing (750 оС + 1050 оС). It is shown that large size Cz-Si ingots have a relatively low concentration of electrically active micro-defects, containing small (0.06 – 0.1 μm) dislocation loops. During thermal treatments this leads to the formation of a low stressed oxide phase (SiO2) with an enhanced thermo-stability. The precipitates in small size ingots, however, contain distorted 4-fold rings of SiO4 tetrahedra.