High‐contrast 2D etched holes array obtained by direct laser writing on chalcogenide As₂S₃ films

Abstract This paper studies optical, chemical and photoinduced changes in amorphous AsS films, obtained by nanosecond pulsed‐laser ablation of a As₄₀S₆₀ target. The arsenic content of the films is slightly higher than the target composition and depends on the ablation fluence. The photobleaching phenomenon appears after 1–2 min of bandgap laser irradiation. The refractive index diminishes by 0.07 and the transmission approximately doubles. It was established for the first time that films obtained by pulsed laser deposition exhibit a positive resist behavior in amine‐containing etchant. The etching rate of the irradiated film was 0.12 µm/min, while as‐deposited films have lower etching rate. The measured selectivity rate was of 14:1. A 2D high‐quality hole array was produced by direct laser writing and further etching. The unusual behavior can be a result of different glass network formation during the condensation of AsS_n molecules sputtered from the bulk target. This is different from the case of thermally evaporated films where AsS₁ molecules only were identified in gas‐phase by mass spectrometry.