The precise determination of the concentrations of defects at thermal equilibrium in Si and Ge by means of simultaneous measurements of positron annihilation and positron diffusion characteristics

为了精确测定热平衡时Si和Ge中的缺陷浓度，测量了正电子湮没和正电子扩散特性随温度的变化。在1997年建成了超短脉冲单能正电子束流装置和1998年安装了红外加热系统后，分别在300 ~ 1200 K和300 ~ 1600 K测量了Ge和Si的正电子湮没特性。在Ge中，正电子湮没特性在300 ~ 600 K之间基本保持不变，在600 K以上开始略有变化，但正电子扩散长度在300 ~ 600 K之间大幅减小，在600 K以上基本保持不变。发现除了向更高温度的偏移之外，总体温度依赖性几乎与Ge中的相同。与Ge相比，论高温下的缺陷 ...更多信息 在Si中的Al平衡中，两个观察报告了矛盾的结果;一个是基于质子辐照产生的内部^<22>Na源，另一个是基于使用Pelletron加速器的β-伽马符合技术。本文的结果与后者的研究结果是一致的。从本工作的精确结果可以得出结论，在以前的实验中观察到的结果应该是由于在高温下的空位团的生长。通过对实验结果的精确分析，发现中温区正电子湮没特性的微小变化是由于正电子-晶格耦合引起的自陷效应的存在，为了获得FZ-的热平衡缺陷信息，对FZ-的缓慢冷却进行了研究，用2D-ACAR测量方法研究了高温退火和氢退火后的硅晶片的熔化情况。结果，按照所含的氧原子浓度的顺序，在10 - 10 μ cm-3量级的浓度下观察到小的氧化物沉淀、氧置换原子、空位-氧复合物和双空位<15><16><-3>。少

Fort the purpose of precise determination of the concentrations of defects at thermal equilibrium in Si and Ge, the positron annihilation and positron diffusion characteristics were measured as a function of temperature. After constructing the ultra short pulse monoenergetic positron beam in FY1997 and installation of a heating system based on ultra-red light in FY1998, the measurements of positron annihilation characteristics were measured between 300K and 1200K in Ge, and between 300K and 1600K in Si, respectively. In Ge, although the positron annihilation characteristics showed a nearly constant behavior between 300K and 600K and started a slight change above 600K, the diffusion length of positrons showed a big decrease between 300K and 600K and kept a constant value above 600K.In Si, the overall temperature dependence was found to be nearly the same as that in Ge except for the shift to the higher temperature. region as compared with Ge. On the defects at high temperatures at therm … More al equilibrium in Si, two observations reported contradictory results ; one is based on the internal ^<22>Na source produced by proton irradiation, the other is based on the beta gamma coincidence technique using the Pelletron accelerator. The present result is in good agreement with the latter investigation. From the precise result of the present work, it was concluded that the observed results in the former experiment should be due to the growth of vacancy clusters at high temperatures. From the precise analyses of the present results, the observed small change in positron annihilation characteristics in intermediate temperature region was attributed to the presence of self-trapping effect due to positron-lattice coupling.In order to obtain the information on the thermal equilibrium defects, the slow cooling of FZ-, Cz- and Hydrogen-annealed- Si wafers from the high temperature near the melting was examined by the 2D-ACAR measurements. As a result, in the order of contained concentration of oxygen atoms, small oxide precipitates, oxygen substitutional atoms, vacancy-oxygen complexes, and divacancies were observed in the concentration of the order of 10^<15>-10^<16>cm^<-3>. Less