Hydrogen-induced defects in crystalline silicon during growth of an ultrathin a-Si:H layer

Abstract

Hydrogen (H) atom-induced defects in crystalline silicon (c-Si) have been experimentally studied during growth of hydrogenated amorphous silicon (a-Si:H) by H2 diluted silane (SiH4) discharge. The H atom-induced defects are effectively generated at the initial growth of a-Si:H, where H atoms penetrate into c-Si through an ultrathin a-Si:H layer (≲4.0 nm). The generation of such defects is enhanced under the high H-flux condition, i.e. the high H2 dilution. However, the defect generation is strongly suppressed once a relatively-thick a-Si:H layer (≳4.0 nm) is grown over the c-Si surface. Interestingly, Si-related precursors such as SimHn radicals are not efficient to generate such defects. A pure SiH4 discharge is thus beneficial for the suppression of the H atom-induced defects in c-Si during the initial growth of an a-Si:H layer.