Giant photoinduced optical bleaching at room and liquid helium temperatures in Sb/As2S3 multilayered films

We report the observation of giant photo induced optical bleaching in Sb/As2S3 multilayered film at room and liquid He temperatures, when irradiated with 532 nm laser at moderate intensities. The experimental results show a dramatic increase in transmittance near the band gap regime at both the temperatures; however the rates at which transmission change occurs are rather slow at low temperature. The huge change in transmission is due to the photo induced intermixing of As2S3 layer with Sb. Our XPS measurements show that photo induced intermixing occurs through the wrong homopolar bonds, which under actinic light illumination are converted into energetically favored hetropolar bonds.

► The article describes the optical properties change due to photodiffusion at low (4.2 K) and room temperature (300 K) in Sb/As2S3 multilayered film.
► Photoinduced bleaching was followed by a large change in optical bandgap (ΔEg = 0.15 eV) at low temperature and (ΔEg = 0.49 eV) at room temperature.
► The diffusion rate is much slower at low temperature than room temperature.
► Moreover, our experimental results suggest that a significant control of these effects can be achieved by irradiating them at a proper temperature.