Correlation between Er3+ emission and Si clusters in Erbium-doped a-SiOx:H films

Erbium-doped hydrogenated amorphous silicon suboxide films containing silicon clusters (a-SiOx:H) were prepared. The samples exhibited photoluminescence (PL) peaks at around 750 nm and 1.54 μm, which could be assigned to the electron-hole recombination in silicon clusters and the intra-4f transition in Er3+, respectively. We compared annealing behaviors of Si clusters and Er3+ emission and found that Si clusters emission depends strongly upon crystallinity of Si clusters, whereas Er3+ emission is not sensitive to whether it is Si nanocrystals (nc-Si) or amorphous Si (a-Si) clusters. The erbium-doped a-SiOx:H films containing either a-Si clusters or nc-Si have the same kind of Er3+-emitting centers. Based on these results, it is concluded that a-Si clusters can play the same role on Er3+ excitation as nc-Si.