Laser-induced optical photobleaching in Bi-doped Ge30Se70 amorphous thin films

The paper reports the photo-induced effects on the optical and structural properties of ternary Ge30Se70−xBix (x = 5, 10) thin films illuminated with 532 nm green laser light. The material exhibits photo-bleaching nature when exposed to laser light for a prolonged time. The amorphous nature sustains after laser irradiation as detected by X-ray diffraction. The chemical composition of the deposited thin film was examined by energy dispersive X-ray analysis. Field emission scanning electron microscopy investigation showed that the surface morphology was influenced by the laser irradiation. The transmission spectra were collected from UV–Vis-NIR spectroscopy which shows the films exhibit indirect allowed transition. The other optical parameters were calculated from the transmission spectra. The linear optical properties were influenced by the laser-induced phenomena. The photobleaching is explained on the basis of homopolar bond breaking and formation of heteropolar bonds with photon energy. The Raman spectra provided the evidence of photo structural changes in the films.