In situ mitigation of muon-induced defects in high lifetime crystalline silicon

Crystalline silicon is used in >90% of solar cells in production, and requires both high quality material and a good understanding of the charge carrier behaviour within. Muon-based techniques are valuable tools to probe the charge carrier behaviour. However, previous muon experiments demonstrated that high-lifetime crystalline silicon could be damaged on exposure to muons, with formation of defects in the form of electron traps. These defects can be overcome by post-exposure processing, including annealing and deposition of passivating dielectrics (i.e., Al2O3). In this proposal, we seek to modify the experimental setup for silicon experiments – exposing high lifetime silicon to muons at elevated temperatures, within a hydrogen-rich environment, or both – to determine whether these defects can be ‘repaired’ in situ.

当前量产的太阳能电池中，超90%以晶体硅（Crystalline silicon）为基材，其制备既需高品质原材料，也需要对材料内部的载流子行为具备充分的认知。基于μ子（Muon）的探测技术是探究载流子行为的有效工具。但既往的μ子实验显示，高寿命晶体硅在暴露于μ子束流时会受到损伤，形成以电子陷阱为形式的缺陷。这类缺陷可通过曝光后处理工艺予以消除，具体包括退火工艺以及钝化电介质（即三氧化二铝Al₂O₃）的沉积步骤。在本研究提案中，我们拟对晶体硅相关实验的装置进行优化：即在高温环境、富氢环境，或同时兼具两种条件的环境下，将高寿命晶体硅暴露于μ子束流中，以此验证能否在原位修复上述缺陷。