The electrical and optical properties of implanted amorphous silicon

The n-type amorphous silicon hydrogen alloys are prepared by phosphorus ion implantation, followed by thermal annealing and hydrogen passivation. A critical dosage of 5x10/sup15/ is found, beyond which the doping effect become evident and the electrical properties of the film is comparable to the n/sup +/ a-Si:H deposited by glow discharge. From the IR spectra of the highly implanted samples, the SiH/sub x/ species become very small after hydrogen passivation. It is due to the fact that most of the voids are filled by extra P atoms during annealing, so very few hydrogen atoms can be driven into the film. In photoluminescence spectra, the high energy peak at 1.4 eV drops very fast and low energy shoulder at 1.25 eV becomes evident after implantation. It can be explained by Brodsky's quantum well model.