Band offset in boron-doped amorphous silicon heterostructures

Band discontinuities in boron-doped hydrogenated amorphous silicon (a-Si:H)/undoped a-Si1-xNx:H (x = 0.38) and B-doped a-Si1-xCx:H (x = 0.23)/undoped a-Si:H heterojunctions were determined as a function of boron-doping ratio by using X-ray photoelectron spectroscopy (XPS). It is shown that the decrease in the optical band gap of the materials by boron doping arises from the upward shift of the valence band top, while the conduction band edge remains almost unchanged.