Optical properties of doped hydrogenated amorphous silicon films

Abstract

The effect of doping on the reflectance and on the imaginary part of the dielectric function in the UV-visible range was investigated for a series of hydrogenated amorphous silicon films. The samples, doped with phosphorus or boron, were prepared by a reactive evaporation technique. Doping, with either p-or n-type dopants, strongly affects the spectra causing both a red shift and a decrease in peak height. Analysis of the results in terms of the oscillator strength and the excitation energy indicates that there is a decrease in the short-range order which, according to the literature, is attributed to a degree of structural disorder induced by the dopants.