The effects of hydrogen partial pressure on reactively sputtered amorphous silicon

Hydrogenated amorphous silicon films have been reactively sputtered under various hydrogen partial pressures (pH2) from 0 to 3 mTorr in which the partial pressure of argon (pAr) also was varied so as to give a range of bombardment conditions and film microstructures. As pH2 is increased, H is initially incorporated primarily as monohydride. The density of monohydride reaches a maximum and then decreases while the density of dihydride continues to increase. The H/Si atomic ratio increases throughout the entire range of pH2 whereas the density of hydrogen reaches a broad maximum and thereafter decreases. The effects of pH2 and pAr are largely independent, but both have substantial control over film properties. Depostion rate, intrinsic stress, H content and bonding, optical properties, and Pd Schottky barrier photoresponse were measured.