中子辐照对硅片表面氧化层错的抑制作用

对硅片表面氧化层错形成机理进行了探讨。并通过中子辐照在直拉硅中引入缺陷，利用辐照缺陷和硅中氧的相互作用，强烈抑制硅片表面氧化层错的产生。     

Heat-pulse annealing of arsenic-implanted silicon with a CW arc lamp

A new annealing method is introduced whereby a silicon wafer is irradiated by a short heat pulse generated by CW lamps. Results of the annealing process obtained from medium-dose arsenic-implanted silicon are similar to those obtained from nonmelting short heat treatments-complete activation of the implanted dopant with no diffusion or distortion of the impurity profile. Investigation of the crystal structure by means of TEM indicates a lack of any defects down to a resolution of 10 Å. Because of its simplicity, heat-pulse annealing has the potential of higher throughput in comparison to equivalent laser or electron-beam irradiation.     

Effect of a fullerene coating on the photoluminescence of porous silicon

The interaction of a matrix of silicon nanocrystallites (porous silicon layer) with embedded fullerene molecules C₆₀ was studied. The degradation of fullerene-containing layers as a result of irradiation with a strongly absorbed laser light was explored. It is shown that the layers with highest stability are obtained after high-temperature annealing in hydrogen. In this case, the photoluminescence spectra remain virtually unchanged when the layers are kept in air and irradiated with a high-intensity laser irradiation. Possible mechanisms of the phenomena studied are discussed.     

The effect of the charge state of nonequilibrium vacancies on the nature of radiation defects in <Emphasis Type="Italic">n</Emphasis>-Si crystals

The aim of this study is to gain insight into the effect of the charge state of nonequilibrium vacancies on the processes that occur during irradiation and annealing in silicon crystals. n-Si floating-zone crystals with an electron concentration of N = 6 × 10¹³ cm^?3 are irradiated with 25-MeV protons at 300 K. The irradiated crystals are then studied by the Hall method at temperatures ranging from 77 to 300 K. It is shown that the nature and energy spectrum of radiation defects in n-Si crystals are mainly controlled by the charge state of nonequilibrium vacancies.     

Phosphorus doping of silicon by means of neutron irradiation

Phosphorus doping of silicon with the aid of neutron irradiation is a very effective method to produce silicon single crystals with a homogeneous resistivity distribution and an exact average resistivity. The doping process is described and some aspects are given for the handling of the irradiated silicon. Experimental results concerning the resistivity distribution and the accuracy of aim are presented.     

Effect of irradiation with reactor neutrons and the temperature of subsequent heat treatment on the structure of InP single crystals

The results of studying the features of the effect of irradiation with fast and full-spectrum reactor neutrons and subsequent heat treatments on the structural characteristics of InP single crystals are reported. It is shown that, in contrast to other III–V semiconductor compounds, the lattice constant decreases in InP as a result of irradiation with neutrons. Fast neutrons make the major contribution to the variation in the lattice constant. The presence of the component of thermal neutrons that give rise to Sn atoms in the material does not bring about any appreciable variation in the lattice constant. Heat treatment of irradiated samples at temperatures as high as 600°C leads to annealing of radiation defects and recovery of the lattice constant; in the samples irradiated with high neutron fluences, the lattice constant becomes even larger than that before irradiation. An analysis of the obtained experimental data made it possible to assume that the decrease in the InP lattice constant as a result of irradiation with neutrons is mainly caused by the introduction of the P_In antisite defects that give rise to an effect similar to that of vacancy-related defects.     

Effects of electron and neutron irradiation on the electrical properties of Si on MgO·Al2O3 spinel

The effects of electron and neutron irradiation on the electrical conductivity and Hall coefficient of n-type heteroepitaxial (Epi) Si/spinel have been measured and compared to those for bulk vacuum-floating-zone (VFZ) silicon. A smaller degradation rate is observed for conductivity in Epi than in VFZ Si under irradiation. This effect is primarily due to a smaller mobility in Epi compared to VFZ Si, rather than to a lower defect production rate in Epi Si. Epi and VFZ Si exhibit similar carrier removal rates under irradiation, similar relative effects of electron and neutron damage, and similar annealing characteristics below 200°C which include the temperature for vacancy-phosphorus defect annealing. These similarities imply that a major fraction of the irradiation-induced defects are the same in irradiated Epi and VFZ Si at room temperature, even though extensive disorder in the “as grown” Epi Si drastically affects the pre-irradiation mobility. Thus, the inherent initial disorder in heteroepitaxial Si films does not necessarily increase radiation tolerance.     

低功率CO2激光辐照对多层石墨烯结构的影响

在真空环境下使用不同功率密度的CO2激光对化学气相沉积法(CVD)生长的石墨烯进行辐照,通过研究辐照前后的拉曼光谱变化考察了激光功率密度及辐照时间对多层石墨烯结构的影响。结果表明,当功率密度较低(13W/cm2)时,石墨烯拉曼光谱中的D峰降低,2D峰增强,石墨烯内的掺杂、缺陷减少。随着功率密度的增加,石墨烯的缺陷增多,部分缺陷连接形成晶界,使石墨烯分解为纳米晶。在58 W/cm2的功率密度下,当作用时间为120s时,在石墨烯表面产生非晶碳。研究表明,适当参数的CO2激光辐照能改善石墨烯的内在性能。     

Effect of γ irradiation on the photoluminescence kinetics of porous silicon

The effect of γ irradiation on the photoluminescence decay dynamics in porous silicon is investigated. Growth of the photoluminescence intensity and decrease of the decay time in irradiated porous silicon are explained by a lowering of the barriers to recombination of spatially separated electrons and holes via tunneling. The γ irradiation of porous silicon leads to a greater dispersion of the decay time. Fiz. Tekh. Poluprovodn. 33, 1462–1464 (December 1999)     

单脉冲激光损伤CCD探测器的有限元仿真

为了研究激光对CCD探测器的损伤效应,采用有限元分析的方法进行了激光损伤CCD的理论分析和实验验证。阐述了激光辐照CCD探测器的损伤机理,设计了激光辐照CCD探测器热效应的仿真模型,针对波长为532nm的高功率激光辐照硅基CCD探测器而产生的热效应,利用有限元法进行了仿真计算,得到了CCD探测器受到532nm激光辐照时硅电极的温度曲线以及硅电极损伤时间阈值,并相应计算出损伤CCD探测器所需要的激光能量阈值为220mJ/cm2左右。结果表明,损伤阈值随着激光功率密度的增大而减小,但变化幅度不大;当多脉冲毫秒激光辐照CCD探测器,在一个脉冲结束、下一个脉冲到来之前,探测器温度恢复到环境温度。该模型可以较为准确地对单脉冲激光辐照CCD探测器时产生的热损伤效应进行模拟。     

背电场硅太阳能电池离子辐照效应

空间太阳能电池受电子、质子，以及重离子辐照后，要受到损伤。文章对背电场太阳能电池低能质子、高能质子、碳、氧离子辐照效应进行了研究，对辐照前后太阳能电池光电参数进行测量，并用Ｍａｔｔｅ－Ｃａｒｌｏ方法对辐照粒子的硅中的能量损失过程进行了模拟计算。结果表明，各种离子辐照技术电池的损伤是不同的，低能质子对开路电压的损伤比对睡电压的损伤大得多，而高能质子 地开路电压的损伤较低能质子的反而要小，对短路电流的     

长脉冲激光辐照单晶硅的热损伤

为探究毫秒脉冲激光辐照单晶硅的热损伤规律和机理,利用高精度点温仪和光谱反演系统对毫秒脉冲激光辐照单晶硅的温度进行测量。分析温度演化过程,研究毫秒脉冲激光对单晶硅热损伤全过程的温度状态和对应的损伤结构形态。研究表明:脉冲宽度固定时,激光诱导的单晶硅的峰值温度随能量密度的增加而增加;当脉冲宽度在1.5~3.0 ms之间时,温度随脉冲宽度的增加而降减小。温度上升曲线在熔点(1 687 K)附近时出现拐点,反射系数由0.33增加为0.72。在气化和凝固阶段,出现气化和固化平台期。单晶硅热致解理损伤先于热致熔蚀损伤,在低能量密度激光作用条件下,应力损伤占主导地位,而在大能量密度条件下,热损伤效应占主导地位。损伤深度与能量密度成正比,随脉冲个数增加迅速增加。     

Relaxation of a defect subsystem in silicon irradiated with high-energy heavy ions

The relaxation of a silicon defect subsystem modified by the implantation of high-energy heavy ions was studied by varying the electrical properties of irradiated Si crystal annealed at a temperature of 450°C. It is shown that quenched-in acceptors are introduced into Si crystals as a result of irradiation with comparatively low doses of Bi ions and subsequent relatively short annealing (no longer than 5 h); the distribution of these quenched-in acceptors has two peaks located at a depth of about 10 μm and at a depth corresponding approximately to the ions’ projected range (43.5 μm). The peaks in the distribution of quenched-in acceptors correspond to the regions enriched with vacancy-containing defects. As the heat-treatment duration increases, the acceptor centers are transformed into donor centers with the centers’ spatial distribution remaining intact. Simultaneously, an almost uniform introduction of quenched-in donors occurs in the entire crystal beyond the depth corresponding to the projected range of ions. __________ Translated from Fizika i Tekhnika Poluprovodnikov, Vol. 37, No. 5, 2003, pp. 565–569. Original Russian Text Copyright ? 2003 by Smagulova, Antonova, Neustroev, Skuratov.     

Effect of proton irradiation on the breakdown voltage of a high-voltage <Emphasis Type="Italic">p–n</Emphasis> junction

The effect of hydrogen-related shallow thermal donors and acceptor-like defects arising under proton irradiation of silicon on the breakdown voltage of a high-voltage p–n junction is considered. The relations making it possible to compute the breakdown voltage of the irradiated p–n junction taking into account the increase in critical field intensity during the ingress of hydrogen-related shallow thermal donors into the region of collisional ionization of the p–n junction are obtained. A technique for determination of the layer position and the minimum dose of hydrogen-related shallow thermal donors making it possible to decrease the breakdown voltage by a specified amount is proposed.     

Residual stresses in silicon and their evolution upon heat treatment and irradiation

The distributions of internal stresses in undoped and tin-doped silicon and the influence of electron irradiation with an energy of 5 MeV and of heat treatment at 450°C on the stresses are studied. The stresses are measured by a method based on the detection of birefringence by modulation polarimetry. It is shown that tin-doped silicon includes stripes of point defects with a nonuniform distribution of residual stresses of up to 20 kg cm^–2. Heat treatment at 450°C induces an increase in the residual stresses in the sample to 50 kg cm^–2. It is established that the radiation defects formed upon the irradiation of tin-doped silicon reduce the residual stresses to 2–3 kg cm^–2.     

Changes in the state of phosphorus atoms in the silicon lattice as a result of interaction with radiation defects

Interaction of radiation defects with phosphorus atoms in silicon crystals subjected to electron irradiation and thermal treatments was studied under conditions of various degrees of supersaturation with respect to the equilibrium concentration of impurities and point defects. It is shown that, in the course of silicon irradiation, the electron-dose dependences of the phosphorus concentration at the lattice sites (P_s) level off (tend toward a constant value). This constant value is governed by the irradiation temperature. The stages of recovery of the concentration P_s as a result of heat treatments correlate with temperature intervals of dissociation of the vacancy complexes. The results indicate that there are two processes. One process involves the interaction of dopant atoms with silicon self-interstitials and the emergence of interstitial complexes; i.e., this process corresponds to the radiation-stimulated decomposition of a supersaturated solution of an impurity as a result of point-defect generation and ionization. The other process consists in the recombination of interstitial impurities with vacancies at sufficiently high temperatures or in the annihilation of vacancies released during heat treatments with interstitial atoms incorporated into composite defect complexes with the involvement of phosphorus atoms.     

Dynamics of Changes in the Photoluminescence of Porous Silicon after Gamma Irradiation

Radiation stability of the nanoporous silicon under gamma irradiation was investigated. Changes in the properties of porous silicon under gamma irradiation were registered by measurements of photoluminescence spectra and Fourier-transform infrared (FTIR) spectroscopy. Besides the appearance of point defects and their subsequent oxidation, the significant differences were shown to be in the behavior of the porous silicon properties in comparison with that of bulk silicon apparently due to the quantum size nature of nanoporous silicon.     

Quality of the p-Si crystal surface and radiation-stimulated changes in the characteristics of Bi-Si-Al surface-barrier structures

The results of studying radiation-stimulated changes in the electrical characteristics of surfacebarrier structures based on p-Si with different values of resistivity (24 and 10 ?? cm) are reported. The state of the surface of the samples under study has been analyzed using atomic-force microscopy. It is shown that irradiation leads to the evolution of structural defects and a variation in the charge state of already existing defects in the structures based on solar-grade silicon (24 ?? cm). Pyramidal defects are formed in the surface layer of p-Si:B (?? = 24 ?? cm) and partially change their structure as a result of irradiation with X-ray quanta.     

Interaction of copper impurity with radiation defects in silicon doped with boron

The spectrum of deep levels formed in boron-doped Czochralski-grown silicon single crystals as a result of interaction of radiation defects with copper impurity is studied. It is shown that, irrespective of the order of introduction of defects (both in the case of low-temperature copper diffusion into crystals preliminarily irradiated with electrons and in the case of irradiation of the samples contaminated with copper), the same set of deep levels appears. In addition to conventional radiation defects, three types of levels have been detected in the band gap of copper-containing crystals. These levels include the level E _v + 0.49 eV (already mentioned in available publications), the level E _v + 0.51 eV (previously not related to copper), and a level close to the donor level of a vacancy. Based on the analysis of concentration profiles, the interstitial carbonoxygen pair is excluded from possible precursors of the copper-containing center with level E _v + 0.49 eV.     

Light-induced E.S.R. in amorphous silicon

A model for defects in hydrogenated amorphous silicon (T_S > 150‡C) observed by light-induced E.S.R. is presented. It is based on a comparison with E.S.R. signals observed from irradiation defects in crystalline silicon. The magnitude of the E.S.R. signal as a function of hydrogen concentration is also discussed.