Investigation on the optical phase change properties of intrinsic GeSb and Ti-doped GeSb

Abstract

In this work, GeSb and Ti-doped GeSb thin films were fabricated by the magnetron sputtering method and the optical phase change properties were systematically investigated through both experimental analyses and DFT calculation. High reflectivity contrast between amorphous and crystalline phase was observed in non-doped GeSb with a stable optical response at 480°C, leading to outstanding optical phase change capability. The red-shift of the optical absorption peak was studied, reflecting in the modulation of the electronic structure in GeSb during thermal-induced crystallization. With the introduction of Ti dopant, crystallization of GeSb was suppressed. A blue-shift trend of band-gap was clearly observed with the increase of Ti concentration, speculating a negative influence of phase change capability, thus resulting in the sharp decrease of optical reflectivity contrast by 10% at the visible wavelength.