Linear and non-linear optical properties of amorphous Se and M5Se95 (M = Ge, Ga and Zn) films

Abstract

The variations in structure and optical properties of amorphous a-Se and a-M5Se95 (M = Ge, Ga and Zn) films have been studied based on FTIR and optical measurements. FTIR transmittance spectra for a-Se and a-M5Se95 (M = Ge, Ga and Zn) glasses were measured as a function of wavenumber. The addition of Ge, Ga and Zn increases the vibrational frequency of the a-Se main band. The absorption edge of Ge5Se95 shifted towards long side of the wavelength in comparison with that of a-Se film. This shift increases gradually in the case of Ga5Se95 and Zn5Se95 films. So, the optical bandgap ofM5Se95 films was decreased, but the index of refraction was increased. The first and third order of electric susceptibility (χ(1) and χ(3)) and non-linear index of refraction (n2) were increased by adding Ge, Ga and Zn into a-Se.