Papers by Keyword: CZ-Si

Abstract: The effect of annealing temperature on oxygen precipitation was investigated in various dose fast neutron irradiated Czochralski silicon (CZ-Si). Fourier Transform Infrared Absorption Spectrometer (FTIR) was used to measure the concentration of interstitial oxygen ([O_i]). Bulk microdefects (BMDs) were observed by optical microscope. The behavior of oxygen precipitation depends on the annealing temperature and the concentration of irradiation-induced defects. The mount of oxygen precipitates of irradiated samples is more than that in non-irradiation samples and increases with increasing the irradiation dose. Because of the effect of temperature on critical radius r_c and the oxygen diffusivity, oxygen precipitation increase with the increase of temperature at the studied lower temperature range, while decrease with the increase of temperature at the studied higher temperature range. High density dislocation and stacking faults generate in irradiated sample.

Abstract: Electron irradiation on silicon results in the creation of vacancy (V) and silicon self-interstitial (I).Vacancy tends to integrate with oxygen and forms the complexes of vacancy and oxygen (V_mO_n) such as VO, VO₂, and VO₃. These complexes of vacancy and oxygen in silicon have been the subject of extended investigations by standard methods such as infrared absorption. In infrared spectrum, the different V_mO_n has the corresponding peak. Irradiation induced defects as the core of oxygen precipitate can accelerate the oxygen precipitation. Oxygen precipitation plays an important role in the internal gettering (IG). In electron irradiated silicon, annealing at 300700 °C leads to the formation of two types of electrically active centers that are shallow thermal acceptors (TAs) and the well-known thermal donors (TDs). In this paper, the generation conditions, the infrared peaks of V_mO_n, the types of oxygen precipitation induced defects, the characters of TAs and TDs are studied.

Abstract: A review of light soaking of solar cells by the use of commercial IV-characterization instruments is presented. The paper addresses the challenges of studying light induced degradation (LID) using a high intensity light source. Issues related to heating of the cell, temporal intensity instability and the impact of the irradiance spectrum are discussed. The main focus of the paper is devoted to the degradation of boron-doped Czochralski silicon (Cz-Si) where boron-oxygen related complexes are responsible for a metastable defect formation. Some advantages and limitations concerning the use of IV characteristics to reveal the degradation properties of boron-doped Cz-Si compared to applying minority carrier lifetime techniques are also presented.

Abstract: Hydrogen gettering by implantation-disturbed buried layers in oxygen-implanted silicon (Si:O, prepared by O2+ implantation at energy 200 keV and doses 1014 cm-2 and 1017 cm-2) was investigated after annealing of Si:O at up to 1570 K, also under enhanced hydrostatic pressure, up to 1.2 GPa. Depending on processing conditions, buried layers containing SiO2-x clusters and/or precipitates were formed. To produce Si:O,H, Si:O samples were subsequently treated in RF hydrogen plasma. As determined by Secondary Ion Mass Spectrometry, hydrogen was accumulated at the sample surface and within implantation-disturbed areas. It was still present in Si:O,H (D=1017 cm–2) even after subsequent annealing at up to 873 K. Hydrogen accumulation within disturbed areas of Si:O as well as of SOI can be used for recognition of defects in such structures.

Abstract: A probing of the atomic environment of positron in Cz-Si single crystal heat-treated at T=600C and T=450C has been performed by one-dimensional angular correlation of annihilation radiation (ACAR). It has been established that positrons get trapped by the oxygen-related complexes. The penetration of positrons into the core region of surrounding atoms results in emission of the elementally specific high-momentum annihilation radiation. The processes of expelling of positron from ion cores and its penetration into the core region are regulated by the potential barrier (to be considered as the Coulomb’s one as a first approximation). The characteristic electron-positron ion radius and the probabilities of correlated events of the highmomentum annihilation are due to the chemical nature of the ion cores of atoms involved in the composition of the oxygen-related complexes. The interpretation of the results is based on the notion of the positron localization in the field of negative effective charge resulted from comparatively high electron affinity of the oxygen impurity atom. The presence of a free volume (perhaps, a vacancy) as well as the carbon atom in the microstructure of the oxygen-related positron-sensitive thermal defects is briefly discussed.

Abstract: Effect of hydrostatic pressure (HP) on out – annealing of defects in self – implanted silicon (Si:Si, Si+ doses 5x1016 cm-2 and 1x1017 cm-2, energies 50 keV and 160 keV), treated for 1 – 10 h at up to 1400 K (HT) under HP ≤ 1.4 GPa, has been investigated by photoluminescence, X-ray and related methods. Applied at 720 – 1270 K enhanced pressure does not affect or affects adversely Si:Si structure while at 1400 K assists in its improvement. HP – dependent transformations in Si:Si at HT are related to effect of HP on diffusion of point defects, such as silicon interstitials and vacancies produced at implantation. Out - annealing of defects in self - implanted silicon is dependent also on spatial position of damaged areas in Si substrate.

Abstract: Oxygen precipitation and creation of defects in Czochralski grown silicon with interstitial oxygen concentration 9.4·1017 cm-3, subjected to irradiation with neutrons (5 MeV, dose 1x1017 cm-2) and subsequently treated for 5 h under atmospheric and high hydrostatic pressures (HP, up to 1.1 GPa) at 1270 / 1400 K, were investigated by spectroscopic and X - Ray methods. Point defects created by neutron irradiation stimulate oxygen precipitation and creation of dislocations under HP, especially at 1270 K. The effect of pressure treatment is related to changed concentration and mobility of silicon interstitials and vacancies as well as of the VnOm – type defects.