A study was made of the effect of rapid thermal annealing upon the room-temperature photoluminescence of amorphous H-doped thin films which had been prepared by plasma-enhanced chemical vapor deposition. It was found that the photoluminescence intensity increased by an order of magnitude after annealing (800C, 1200s), as compared with as-deposited samples. Changes in the materials were monitored by means of  in situ  real-time ellipsometry. The results suggested that the annealing involved 2 distinct mechanisms. The first consisted of H effusion from clustered H and/or =N-H bond breaking which occurred within the first 300s; resulting in an increased dangling-bond density and no increase in photoluminescence intensity. The second occurred after longer annealing times, due to the local reconstruction of Si-O and Si-N bonds rather than to diffusional rearrangement of the atomic species. This resulted in a denser material with a higher refractive index, fewer non-radiative recombination centers, and more efficient photoluminescence. A model was developed which described both radiative and non-radiative recombination.

B.H.Augustine, Y.Z.Hu, E.A.Irene, L.E.McNeil: Applied Physics Letters, 1995, 67[25], 3694-6