Thermal Equilibrium Defects in Hydrogenated Amorphous Silicon Based Alloy Films

ABSTRACTBoth the temperature dependence at elevated temperature and the increase after fast cooling from elevated temperature of the density of dangling bonds are measured by ESR for undoped hydrogenated amorphous silicon–based alloy films, a–Si:H, a–Si1−xCx:H, a–Si1−xNx:H and a–Si1−xOx:H. Both a–Si:H and a–Si1−xCx:H clearly show the increase in the density of dangling bonds at elevated temperature, while the increase is less prominent for a–Si1−xNx:H and a–Si1−xOx:H. The observed results for both a–Si:H and a–Si1−xCx:H are fairly well reproduced by the model recently proposed by Smith et al. The results of CPM measurements combined with those of ESR measurements suggest that the density of charged dangling bonds present in undoped a–Si:H also increases after fast cooling from elevated temperature.