CONTROL OF POWDER FORMATION IN SILANE DISCHARGE BY CATHODE HEATING AND HYDROGEN DILUTION FOR HIGH-RATE DEPOSITION OF HYDROGENATED AMORPHOUS-SILICON THIN-FILMS

Hydrogenated amorphous silicon (a-Si:H) films have been deposited at high growth rates by increasing the rf power density while the optoelectronic quality of the films has been concurrently taken care of by controlling powder formation due to gas-phase polymerization in the plasma. This has been achieved by heating the cathode together with the anode in the capacitive coupling arrangement and keeping the cathode temperature close to that of the anode. This, together with hydrogen dilution of the source gas, has been used to control powder formation in the silane discharge. The films have been evaluated by optical and infrared vibrational spectroscopy, dark conductivity, secondary photoconductivity, and internal quantum efficiency measurements.