The integrity of the hydrogenated amorphous silicon/crystalline silicon (a-Si:H/c-Si) interface is essential for the enhanced performance of a-Si:H/c-Si heterojunction-based devices. However, during annealing processes aimed at passivating silicon dangling bonds, unexpected Si epitaxy and nanotwin formation tend to emerge, even under low-temperature conditions. Therefore, understanding the influence of such annealing on the a-Si:H/c-Si interfacial structure is therefore pivotal for device optimization. In this study, the atomic-scale structural transformation of the a-Si:H/c-Si heterointerface subjected to low-temperature annealing is delved into. The dynamic evolution of this interface is captured by employing in situ spherical aberration (C_S)-corrected transmission electron microscopy (TEM), molecular dynamics (MD) simulations, and density functional theory (DFT) calculations. The TEM observations indicated that Si epitaxy initiated before Si nanotwin formation, and these nanotwins are inclined to revert to epitaxial structures upon sustained annealing. Through MD and DFT insights, the thermodynamic and kinetic intricacies driving the concerted tri-layer atomic shift characterizing the Si nanotwin-to-epitaxy transition are decoded. The findings shed light on the thermal behavior of a-Si:H/c-Si interfaces, offering new perspectives on the thermal management in silicon heterojunction devices.

中文翻译：

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低温热退火过程中 a-Si：H/c-Si 异质界面的原子尺度结构动力学


氢化非晶硅/晶体硅 （a-Si：H/c-Si） 界面的完整性对于增强基于 a-Si：H/c-Si 异质结的器件的性能至关重要。然而，在旨在钝化硅悬空键的退火过程中，即使在低温条件下，也容易出现意想不到的硅外延和纳米孪晶形成。因此，了解这种退火对 a-Si：H/c-Si 界面结构的影响对于器件优化至关重要。在本研究中，深入研究了低温退火作用下的 a-Si：H/c-Si 异质界面的原子级结构转变。该界面的动态演变是通过采用原位球差_（CS） 校正透射电子显微镜 （TEM）、分子动力学 （MD） 模拟和密度泛函理论 （DFT） 计算来捕获的。TEM 观察表明，Si 外延在 Si 纳米孪晶形成之前开始，并且这些纳米孪晶在持续退火后倾向于恢复为外延结构。通过 MD 和 DFT 的见解，解码了驱动 Si 纳米孪晶到外延转变的协同三层原子位移的热力学和动力学复杂性。这些发现阐明了 a-Si：H/c-Si 界面的热行为，为硅异质结器件的热管理提供了新的视角。