Improvement in the optical absorption of PECVD microcrystalline Si thin film through modification of the crystalline fraction through an annealing process

摘要

Intrinsic microcrystalline silicon (mu c-Si) thin films with varying crystalline fractions (X-C) were deposited using plasma-enhanced chemical vapor deposition Effort was made to modify the X-C and optical properties by annealing at different temperatures, pressures, and ambient gases After annealing, the amount of Si-H in the mu c-Si thin film was decreased for an initial X-C of 7%, while that of Si-H-2 mainly decreased to an initial X-C of 60-70%. The X-C of mu c-Si with an initial X-C of 7% increased by annealing. However, initial X-C of 60% and 70% resulted in a decrease of X-C upon annealing. It is suggested that an increase in crystal size of mu c-Si films by annealing decreases X-C, while a decrease in crystal size increases X-C. Depending on the annealing conditions, the optical absorption property of the mu c-Si thin film changed. When the initial X-C was 7%. the absorption coefficient increased as X-C increased to 16%, but slightly decreased with X-C values from 51% to 70% Therefore, we suggest that there is an optimum X-C that exhibits the highest optical absorption (C) 2009 Elsevier B V All rights reserved.