Laser‐Induced Formation of CdS Crystallites in Cd‐Doped Amorphous Arsenic Sulfide Thin Films

Abstract

As 2 S 3 :Cd films with nominal Cd content x up to 4 at.% were prepared by thermal evaporation. Their amorphous structure is confirmed by Raman spectroscopy. The film surface roughness estimated from atomic force microscopy does not exceed 1 nm. Energy‐dispersive X‐ray spectroscopy and X‐ray photoelectron spectroscopy show a strong decrease of Cd content with the film depth. Peaks of CdS longitudinal optical phonon and its overtones emerging in the Raman spectra of films with x ≥ 2 at.% Cd are the evidence for the laser irradiation‐induced formation of CdS crystallites in the As 2 S 3 :Cd films. The downward shift of the CdS Raman peak frequencies is mainly explained by tensile strain undergone by the CdS crystallites in the films caused by material transfer from the laser spot due to the photoplastic effect.