Changes in surface topography of amorphous silicon germanium films after light soaking

Light-induced metastable degradation of hydrogenated amorphous silicon and silicon germanium thin films (a-SiGe:H) is conjectured to be accompanied by structural changes but there has not been a direct measurement of the same. We measure the surface topography of these films in the annealed and the light soaked state using atomic force microscopy. We quantified the surface topography in terms of surface roughness and find that the surface roughness increases after light soaking. Our results provide direct evidence of the light-induced structural changes in these films. (c) 2007 American Institute of Physics.