Silicon Thin-Film Formation by Direct Photochemical Decomposition of Disilane

Silicon thin-films have been deposited by the direct photolysis of disilane at a substrate temperature below 300°C. The growth rate depends on irradiation intensity of a low pressure mercury-lamp, and a typical rate of 15 A/min has been obtained under ~0.08 watts/cm2 illumination, regardless of substrate temperature. The deposited films are composed of an amorphous network containing bonded-hydrogen in the range 6–9 at.%. The bonding configurations of SiH groups varied from silicon dihydride to monohydride with increasing substrate temperature, and correspondingly the dark conductivity decreased from 10-7 to 10-11 Ω-1cm-1. A broad photoluminescence peak at 1.4 eV was observed for a specimen grown at 200°C.