SF6 SENSITIZED CO2-LASER CVD OF AMORPHOUS-SILICON

Sensitized CW CO2 laser CVD of a-Si:H from SiH4 Was performed with SF6 as a strong but chemically inert absorber. Relative to CO2 laser CVD without SF6, the CO2 laser Power, the total and the silicon hydride pa rtial pressures could be substantially reduced. The processing gas was investigated by in situ mass analysis. Polysilanes (SinH2n+2, n great er-than-or-equal-to 3) were not detected. The a-Si:H thin films obtain ed with SF6 sensitized CO2 laser CVD at a substrate temperature of 300 -degrees-C contained about 10 at% of hydrogen compared to 20-25 at% wi th conventional CO2 laser CVD. Furthermore, the maximum photoconductiv ity of the a-Si:H thin films could be raised from below 10(-5) OMEGA-1 . cm-1 to 10(-4) OMEGA-1 . cm-1 using SF6 sensitization.