Institute of Materials Physics, Westfälische Wilhelms-Universität Münster, 48149 Münster, Germany.
Institut für Experimentelle und Angewandte Physik, Universität Regensburg, 93040 Regensburg, Germany.
Phys Rev Lett. 2018 Jun 1;120(22):225902. doi: 10.1103/PhysRevLett.120.225902.
Experiments on self-diffusion in amorphous silicon (Si) were performed at temperatures between 460 to 600° C. The amorphous structure was prepared by Si ion implantation of single crystalline Si isotope multilayers epitaxially grown on a silicon-on-insulator wafer. The Si isotope profiles before and after annealing were determined by means of secondary ion mass spectrometry. Isothermal diffusion experiments reveal that structural relaxation does not cause any significant intermixing of the isotope interfaces whereas self-diffusion is significant before the structure recrystallizes. The temperature dependence of self-diffusion is described by an Arrhenius law with an activation enthalpy Q=(2.70±0.11) eV and preexponential factor D_{0}=(5.5_{-3.7}^{+11.1})×10^{-2} cm^{2} s^{-1}. Remarkably, Q equals the activation enthalpy of hydrogen diffusion in amorphous Si, the migration of bond defects determining boron diffusion, and the activation enthalpy of solid phase epitaxial recrystallization reported in the literature. This close agreement provides strong evidence that self-diffusion is mediated by local bond rearrangements rather than by the migration of extended defects as suggested by Strauß et al. (Phys. Rev. Lett. 116, 025901 (2016)PRLTAO0031-900710.1103/PhysRevLett.116.025901).
在 460 至 600°C 的温度下对非晶硅（Si）的自扩散进行了实验。非晶硅结构是通过 Si 离子注入在绝缘体上硅晶片上外延生长的单晶硅同位素多层结构制备的。退火前后的 Si 同位素分布通过二次离子质谱法确定。等温扩散实验表明，结构弛豫不会导致同位素界面的任何明显混合，而在结构再结晶之前自扩散是显著的。自扩散的温度依赖性由阿仑尼乌斯定律描述，激活焓 Q=（2.70±0.11）eV，前置指数因子 D_{0} =（5.5_{-3.7}^{+11.1}）×10^{-2}cm^{2}s^{-1}。值得注意的是，Q 等于非晶硅中氢扩散的激活焓，键缺陷的迁移决定了硼的扩散，以及文献中报道的固相外延再结晶的激活焓。这种紧密一致提供了强有力的证据，表明自扩散是由局部键重排介导的，而不是由 Strauß 等人提出的扩展缺陷迁移介导的。（物理评论快报 116，025901（2016）PRLTAO0031-900710.1103/PhysRevLett.116.025901）。
