Effect of radio-frequency power and substrate temperature on properties of hot-plasma-box glow-discharge-deposited hydrogenated amorphous silicon carbon alloys

Abstract

The effect of rf power and substrate temperature Ts on the optical, electrical, and structural properties of a-Si1−xCx:H alloy films deposited in the new hot-plasma-box glow-discharge reactor are reported. The rate of deposition as well as the total fraction x of the carbon incorporated in the alloy films were found to vary in a direct proportion with the rf power, whereas the same parameters displayed an inverse proportionality to the changes in Ts. Second, the hydrogen concentration in the alloy films was found to decrease with the increase in substrate temperature while it did not show appreciable variation with the changes in rf power. Next, the structural disorder in the amorphous network was observed to increase rapidly with increase in rf power although a slight improvement was made possible by elevating the Ts. The analysis of Raman scattering and optical band-gap measurements on these alloy films indicates that a large proportion of the Si—C and C—C bond pairs favors the diamondlike (sp3) bonding configuration at low rf power when the Ts is high, whereas the graphitelike (sp2) C—C clusters show up only at high rf power values when the Ts is low. The efficiency of C incorporation in these alloy films prepared by the present technique appears to be better than its best possible magnitude in the conventional open parallel-plate glow-discharge-deposition systems.