Modification of a-Si: H Films via Non-linear Femtosecond Laser Pulse Absorption

The modification of a-Si:H via non-linear femtosecond laser pulse absorption was studied and the characteristic thresholds for hydrogen diffusion/effusion, crystallization and material ablation were determined. To consider the impact of the hydrogen content on laser materials processing, a-Si:H was deposited at different temperatures (25 °C, 200 °C, 520 °C) resulting in different hydrogen contents (30%, 13%, and <1%). Essential information for device applications such as the degree of crystallization and the Si-H dissociation are obtained from micro-Raman spectroscopy of the laser treated areas. The prospects of a flexible non-linear fs laser material processing of a-Si:H for bulk and surface modification will be discussed.