Investigation of the structural and optoelectronic properties of the Se/Ga2S3 heterojunctions

Abstract

In the current study, the structural and optical properties of the Se/Ga2S3 heterojunctions are investigated by means of X-ray diffraction and ultraviolet–visible light spectrophotometry techniques. The optical interface which was prepared by the physical vapor deposition technique, comprises a polycrystalline orthorhombic selenium layer of thickness of 500 nm coated with amorphous layer of 200 nm thick Ga2S3. The top layer is observed to cause yield stress on the Se layer leading to strained type interface. Optically, the evaporation of Ga2S3 onto selenium blue shifted the energy band gap of Se. The conduction and valence band offsets exhibited values of 1.28 and 0.20 eV, respectively. On the other hand, the optical conductivity spectra which were studied and modeled by the Drude-Lorentz approach in the terahertz frequency domain of 275–675 THz revealed enhanced optical conduction parameters. The use of Se as substrate to Ga2S3 enhanced the drift mobility and plasmon frequency of the Ga2S3. The value of the drift mobility reached 64 cm2/Vs at plasmon frequency of 2.04 GHz. In addition, the Se/Ga2S3 interface are observed to exhibit high biasing dependent photosensitivity to visible light irradiation. Such properties of this interface nominate it for use in optoelectronics including visible light communications.