Preparation of high quality and tunable band gap hydrogenated amorphous silicon by homogeneous-CVD (HOMOCVD)

Good-quality a-Si:H films with tunable bandgap have been prepared in a modified conventional low-pressure chemical vapor deposition reactor by homogeneous-CVD (HOMOCVD). After an extensive growth study, a reasonable growth rate (more than 100 A/min) has been obtained. Scanning and transmission electron microscope, optical and infrared absorption, dark conductivity, and photoconductivity measurements were used to characterize the films. In general, the results confirm the findings of B.A. Scott et al. (1981) concerning the high quality of HOMOCVD material. The optical gap of such films could be varied from 1.6 eV to 2.6 eV, the activation energy of the dark conductivity then going from 0.7 eV to 1.4 eV. The versatility of HOMOCVD opens the possibility for photovoltaic and other applications.