Influence of chamber pressure on optoelectronic and structural properties of boron-doped hydrogenated silicon films prepared by rf magnetron sputtering

Abstract

Results on the characterisation of boron-doped hydrogenated silicon films prepared by rf magnetron sputtering technique are presented. The effects of chamber pressure on the structure and electronic properties of the films were investigated. The films were characterised by conductivity and thermoelectric power measurements, optical absorption and reflectance (specular and diffuse) measurements, X-ray diffraction analysis, infrared vibrational spectroscopy, Raman spectroscopy and scanning electron microscopy. The structural characteristics were correlated with the conductivity and thermoelectric power. With increase in pressure the growth pattern changed from an amorphous one, with poor structural and optoelectronic properties, to one which was crystalline, with improved structural ordering. In the intermediate range of pressure growth was mainly expected to be governed by BH₃ radicals. With further increase in pressure, segregation of boron atoms with concomitant deterioration in crystalline structure was observed. The features were however distinct from those of the amorphous films obtained at low pressures probably due to the increased role of atomic hydrogen at higher pressures.