共查询到16条相似文献,搜索用时 62 毫秒
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本文通过红外吸收光谱技术研究了不同剂量快中子辐照直拉硅中空位氧缺陷(A中心)的退火行为.实验发现,经200℃热处理后样品中均会出现V2O (840 cm-1)和VO2 (919.6 cm-1)的红外吸收峰;当退火温度升高到400至450℃之间,在低剂量辐照样品(SL)的红外吸收光谱中会有较强的VO2 (889 cm-1)的吸收峰,而在高剂量辐照样品(SH)中则会有较强的V2O2(825 cm-1)和VO2(919.6 cm-1)的吸收峰.分析认为,在低剂量辐照样品中VO主要是通过与Oi结合形成稳定的VO2而消失;而在高剂量辐照条件下VO则是通过相互结合形成V2O2或与Oi结合形成VO2而消失. 相似文献
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在温度为60~80℃的条件下用剂量为1.72×1019n/crm2的中子对6H-SiC晶体进行了辐照,利用X射线衍射等方法观测了中子辐照引起的缺陷及其恢复.重点追踪6H-SiC的(006)、(0012)晶面的衍射峰并进行实验观测.中子辐照对晶体造成了严重的损伤,使其内部产生了大量的缺陷,在某些被测晶面甚至出现非晶化.通过等时退火,缺陷逐渐消失,晶格开始恢复,其恢复特性由退火温度决定.通过X射线衍射峰的峰高和峰型发现,在温度低于600℃时,辐照损伤几乎不变,超过600℃后,温度越高,晶格恢复现象越明显.原来经辐照呈非晶化的晶面逐渐恢复有序,(006)面衍射峰的半高宽随退火温度的升高呈线性恢复.利用此种线性规律可以制作无线传感器,从而实现对某些复杂环境的温场测试. 相似文献
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首次测量了同成分和掺铁铌酸锂晶体中氧空位的生成焓,发现掺铁可以使铌酸锂晶体中氧空位生成焓大为降低。讨论了实验结果,并提出光折变铌酸锂晶体的还原处理可以在较低的温度下进行。 相似文献
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对经过电子辐照的n型[111]晶向直拉硅样品在不同气氛下进行了热处理,对比研究了热处理气氛对电子辐照直拉硅中的缺陷形貌、间隙氧含量的变化以及清洁区的影响.实验结果表明,热处理气氛对辐照样品中的缺陷形貌影响较大:氩气氛下退火样品体内的缺陷以位错环为主而氮气氛下则主要是层错,并对此现象的机理进行了讨论;经历不同气氛快速预处理再进行高温一步退火后,辐照样品表面会产生一定宽度的清洁区,而氮气氛下清洁区宽度较窄;通过傅里叶变换红外光谱仪检测间隙氧含量的变化发现氮气氛下退火的样品间隙氧含量下降较多,说明氮气氛热处理更有利于氧沉淀的生成. 相似文献
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在60~80℃用剂量为1.67×1020n/cm2的全能谱中子对掺氮6H-SiC晶体进行了辐照,对辐照样品从室温至1600℃进行了等时退火,研究了辐照和退火对样品电学性能的影响.大剂量中子辐照在晶体内产生了大量缺陷和损伤,并引起样品的电学性能发生变化,使电阻率升高、介电常数和介电损耗减小.测试表明:在辐照缺陷及其电学性能的退火演化过程中,存在约为1 000和1400℃两个特征温度.当退火温度低于1 000℃时,随着退火温度的升高,电阻率小幅增加,而介电常数和介电损耗亦下降;在退火温度高于1 000℃时,电阻率开始下降.在退火温度高于1 400℃时,电阻率急剧地下降,而介电常数和介电损耗快速地增加.以间隙原子和空位为缺陷的主要形式作为辐照损伤的模型,对上述现象做了定性解释.测试还表明,掺氮6H-SiC的介电常数高达3.5 x 104,这一奇特的物性主要来源于电子的长程迁移极化. 相似文献
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Silicon - Neutron detectors are extensively used in numerous applications such as, in nuclear fuels plants, high energy accelerators, space explorations, imaging etc. Among the commercially... 相似文献
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On the surface of single crystal silicon wafers, porous layers can be formed by electrochemical etching and their structural properties are determined by the doping type and concentration of the substrate. In p+-type doped, (1 0 0) oriented wafers the porous structure consists of tube-like voids and column-like remains of the silicon matrix, all perpendicular with respect to the wafer surface. In small angle neutron scattering experiments the micrometer long and nanometer diameter elongated scattering elements, i.e., tubes and columns can be well represented and approximated by cylindrical form factors. In an earlier experiment the diameter and scattering length distribution of the cylindrical scattering elements were measured in a p+-type (1 0 0) oriented porous silicon wafer [G. Kádár, G. Káli, Cs. Dücsõ, and E.B. Vázsonyi, Physica B 234–236, 1014 (1997)] and the tube diameters were seen to vary in the range from about 10 to 24 nm. In this paper the continuing small angle neutron scattering study of porous silicon layers will be presented. The evaluation conditions and method for the measured neutron intensity distributions will be discussed. The pore diameter distribution data calculated from the neutron scattering intensity curves are collected and compared in various samples of (1 0 0) oriented p+-doped wafers prepared with different porosity and different layer depth. The structural results and data obtained by small angle neutron scattering experiments may help in understanding the practically useful chemical, electronic and other properties of porous silicon. 相似文献
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Guo-Dong Zhan Mamoru Mitomo Hidehiko Tanaka Young-Wook Kim 《Journal of the American Ceramic Society》2000,83(6):1369-1374
The effect of annealing with and without applied pressure on the microstructural development and phase transformation was investigated in fine-grained β-SiC ceramics containing α-SiC seeds. Materials annealed without pressure had a microstructure consisting of elongated grains, while materials annealed with pressure showed a duplex microstructure consisting of small matrix grains and some of elongated grains. However, annealing with pressure (25 MPa) was found to greatly retard phase transformation from β→α polytypes and inhibit grain growth. This change in lattice parameter suggests that the retardation of phase transformation and grain growth might be attributed to a reduced mass transport rate, which is the result of Al being introduced into the SiC by the annealing pressure. 相似文献
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Silicon - Porous silicon (PSi) samples were irradiated in the epithermal neutron spectrum for 17 h and drastic changes were observed in its electrical, optical and morphological... 相似文献