Density of Gap States in Undoped and Doped Amorphous Hydrogenated Silicon Obtained by Optical Spectroscopy

Abstract

Density of states (DOS) in the mobility gap of amorphous hydrogenated silicon (a-Si:H) is an important parameter since it directly influences the electrical and photoelectrical properties of this material. The silicon dangling bond is a basic deep defect in a-Si:H, the energy position of which is a function of its electron occupation. This defect has been extensively studied by electron spin resonance, luminescence, optical absorption, photoconductivity, conductivity and capacitance techniques1,2 but there exists still strong disagreement about the position of the silicon dangling bond3 within the gap.