Preparation of highly photoconductive hydrogenated amorphous silicon carbide films with a multiplasma-zone apparatus

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Abstract
Highly photoconductive hydrogenated amorphous silicon carbide (a‐SiC:H) films were prepared by alternating monolayer deposition and hydrogen passivation by the plasma‐assisted chemical vapor deposition technique with a multiplasma‐zone apparatus. With this apparatus, the hydrogen‐coverage factor of the growing film surface was increased by the hydrogen plasma in the H‐passivation zone. The a‐SiC:H films grown by repeating deposition of the 3‐Å‐thick layer on the hydrogen‐covered surface showed lower densities of spin and tail states than those of continuously deposited films. Infrared spectra showed that absorption intensities of the carbon polyhydride modes (2890 and 2940 cm−1) decreased and those of the silicon monohydride mode (2000 cm−1) increased with decreasing stacking layer thickness, which suggested formation of a dense network structure. The hydrogen‐coverage factor of the growing film surface was estimated from the dependence of carbon content in the film on the hydrogen‐passivation time and the stacking layer thickness. Under optimized conditions, the film with a photoconductivity of 3×10−5 S/cm and an optical gap of 1.91 eV was prepared.