Interplay of amorphous silicon disorder and hydrogen content with interface defects in amorphous/crystalline silicon heterojunctions

We analyze the dependence of the interface defect density D(it) in amorphous/crystalline silicon (a-Si:H/c-Si) heterojunctions on the microscopic properties of ultrathin (10 nm) undoped a-Si:H passivation layers. It is shown that the hydrogen bonding and network disorder, probed by infrared- and photoelectron spectroscopy, govern the initial D(it) and its behavior upon a short thermal treatment at 200 degrees C. While the initial D(it) is determined by the local and nonequilibrated interface structure, the annealed D(it) is defined by the bulk a-Si:H network strain. Thus it appears that the equilibrated a-Si:H/c-Si interface does not possess unique electronic properties but is governed by the a-Si:H bulk defects. (C) 2010 American Institute of Physics. [doi:10.1063/1.3455900]