Dispersive hydrogen diffusion in an illuminated undoped a-Si:H film as a function of annealing temperature

The dependence of the dispersion parameter α and of the time dependent diffusion parameter D_H (t_L) (estimated over a fixed diffusion length L) on annealing temperature T_a was investigated with elastic-recoil detection analysis (ERDA) in an undoped a-Si:H sample. We found that the α dark value increases with T_a as already observed by other groups, and that the illuminated α value also increases. But we observe that D_H (t_L), measured under illumination, deviates from an Arrhenius law, while D_H (t_L) measured in the dark follows an Arrhenius behavior. <br><br> The hydrogen diffusion mechanisms under intense illumination are discussed in the framework of existing models.