IMPORTANCE OF ARGON PRESSURE IN THE PREPARATION OF RF-SPUTTERED AMORPHOUS SILICON-HYDROGEN ALLOYS

The influence of argon partial pressure P//A//r on the photoconductivity, four-probe conductivity and photoluminescence of rf-sputtered a-Si-H alloys is reported. As p//A//r is increased from 5 to 30 mTorr, for fixed hydrogen partial pressure p//H, photoconductivity increases by as much as three orders of magnitude and then saturates. Over this range the dark conductivity activation energy decreases, a plot of log conductivity versus inverse temperature becomes increasingly less linear and the photoluminescence intensity increases slightly and then drops back. It is noted that high p//A//r films become slowly contaminated upon exposure to air. These results are interpreted in terms of a reduction in energetic silicon atom bombardment of the growing film with increased p//A//r.