Abstract
The variations in structure and optical properties of amorphous a-Se and a-M
5
Se
9
5
(M
=
Ge, Ga and Zn) films have been studied based on FTIR and optical measurements. FTIR transmittance spectra for a-Se and a-M
5
Se
9
5
(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 Ge
5
Se
9
5
shifted towards long side of the wavelength in comparison with that of a-Se film. This shift increases gradually in the case of Ga
5
Se
9
5
and Zn
5
Se
9
5
films. So, the optical bandgap of M
5
Se
9
5
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 (
n
2
) were increased by adding Ge, Ga and Zn into a-Se.