Patterning of WOx, VOx, and MoOx thin-films with picosecond and nanosecond laser sources

Abstract

Transition metal oxide (TMOs) layers have interesting properties as selective contacts, i.e., hole or electron transport layers for novel semiconductor devices. Especially, oxides of molybdenum (MoO3), vanadium (V2O5), and tungsten (WO3) show good bahaviour acting as front hole-selective contacts for n-type crystalline-silicon heterojunction solar cells. Laser scribing has been widely used for thin-film ablation and seems the appropriate technology for device manufacturing with such non-conventional materials. In this work, we study the laser scribing of non-stoichiometric evaporated WOx, VOx, and MoOx films with three different wavelengths (1064, 532, and 355 nm) with pulse duration in the nanosecond and picosecond regimes. The selection of the proper laser source allows a wide parametric window, with complete removal of the TMO films and no alteration of the silicon substrate. The results on the isolation of diodes and their electrical characteristics show the quality of the laser scribing processes.