Ion-induced interface defects in a-Si:H/c-Si heterojunction: possible roles and kinetics of hot mobile hydrogens

Abstract

Interface defects in state-of-the-art semiconductors have a strong impact on device performance. These defects are often generated during device fabrication, in which a variety of plasma processing is used for deposition, etching and implantation. Here, we present the ion-induced defects in hydrogenated amorphous silicon (a-Si:H) and crystalline silicon (c-Si) heterojunction. The experiments of argon ion (Ar+) irradiation over an a-Si:H/c-Si stack are systematically performed. The results suggest that the defects are generated not only by the impact of Ar+ (i.e. well-known effects), but also by another unique effect associated with “hot” mobile hydrogens (H). The mobile H atoms generated near the a-Si:H surface by the impact of Ar+ diffuse deeper, and they generate the a-Si:H/c-Si interface defects such as dangling bonds. The diffusion length of mobile H is determined to be 2.7 ± 0.3 nm, which indicates efficient reactions of mobile H with weak bonds in an a-Si:H network structure.