Abstract For application as precursor layers for silicon solar cells fabricated by laser liquid phase crystallization, thick amorphous silicon films on glass are of interest. However, for hydrogenated amorphous silicon (a-Si:H) precursor layers containing about 10 at.% hydrogen, hydrogen needs to be removed prior to liquid phase crystallization to avoid bubble formation and peeling. For this purpose, an at least 12 hours annealing procedure up to 550°C is considered necessary thus involving long process time and high costs. In this article, we investigate the use of thick hot wire grown a-Si:H films which turn out to need considerably less time for dehydrogenation than dense plasma-grown a-Si:H. The dehydrogenation process is studied by depth profiles of hydrogen concentration and medium range order (MRO) using Raman spectroscopy analysis at etch pits. The results show already at an annealing temperature of 450°C the disappearance of all detectable H in the substrate-near part and the complete removal of H at 550°C after about 4 hours annealing. We attribute this rather fast hydrogen removal to the formation of interconnected voids primarily in the substrate-near range. In the same range of the film, we find a correlation between hydrogen concentration and medium range order suggesting that a silicon network reconstruction due to hydrogen out-diffusion causes an observed decrease of reciprocal MRO. The results stress the importance of void-related microstructure in the a-Si:H for hydrogen removal at a rather low annealing temperature and short annealing time. Our results suggest that hot wire a-Si:H films which can be grown with a high deposition rate and a rather pronounced void-related microstructure may be well suited as economic precursor layers.

中文翻译：

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退火对厚热线生长的 a-Si:H 薄膜的氢浓度和微观结构影响的拉曼光谱分析，该薄膜旨在作为结晶薄膜硅的前体层

摘要 对于作为激光液相结晶制造的硅太阳能电池的前驱体层的应用，玻璃上的厚非晶硅薄膜受到关注。然而，对于包含约 10 at.% 氢的氢化非晶硅 (a-Si:H) 前驱体层，需要在液相结晶之前去除氢以避免气泡形成和剥离。为此，认为需要在高达 550°C 的温度下进行至少 12 小时的退火程序，因此需要较长的工艺时间和较高的成本。在本文中，我们研究了厚热丝生长的 a-Si:H 薄膜的使用，结果证明与致密等离子生长的 a-Si:H 相比，脱氢所需的时间要少得多。脱氢过程通过氢浓度和中程有序 (MRO) 的深度分布在蚀刻坑处使用拉曼光谱分析进行研究。结果表明，在 450°C 的退火温度下，基板附近部分中所有可检测到的 H 消失，并且在 550°C 下退火约 4 小时后，H 完全去除。我们将这种相当快的氢去除归因于主要在基板附近范围内形成互连空隙。在薄膜的同一范围内，我们发现氢浓度和中程阶数之间存在相关性，这表明由于氢外扩散导致的硅网络重建导致观察到的互易 MRO 降低。结果强调了 a-Si 中与空隙相关的微观结构的重要性：H 用于在相当低的退火温度和较短的退火时间内去除氢。我们的结果表明，可以以高沉积速率和相当明显的空隙相关微观结构生长的热丝 a-Si:H 薄膜可能非常适合作为经济的前体层。