In situ ESR study to detect the diffusion of free H and creation of dangling bonds in hydrogenated amorphous silicon -: art. no. 245204

In situ electron spin resonance (ESR) was studied during exposure of hydrogenated amorphous silicon (a-Si:H) films to atomic hydrogen (H) generated by a remote plasma. A high diffusion coefficient of free atomic H (>10(-10) cm(2) s(-1)) is observed in a-Si:H films at the very initial stage of H treatment. The H creates additional dangling bonds (similar to 10(13) cm(-2)) during in-diffusion. The diffusion mechanism of such free H is a self-limiting process. The dangling bonds created at the very initial stage of H exposure act as the trapping sites for the impinging H atoms. Consequently, the effective diffusion coefficient (D-eff) reduces with H treatment time. The D-eff for plasma in-diffusion of H with a relatively wide time span reported in literature is considered to be the resultant of the diffusion coefficient of free H and the bonded H. The characteristic depth of dangling-bond distribution decreases with increasing H treatment temperature. The activated rate constants of db creation reactions dominate over the activated free-H diffusion to determine the distribution of additional dangling bonds at different treatment temperatures.