Abstract
Measurements of optical constants of thin films of GaxSe100-x nanoparticles with x = 3, 6, 9 and 12 have been made in a wavelength region 400-900 nm. The experimental results show that the optical absorption follows the rule of indirect transition. The optical band gap and optical constants of thin films have been studied as a function of photon energy. It has been observed that the optical band gap increases with an increase in the Ga concentration in Ga-Se system while, the refractive index, extinction coefficient, real part of dielectric constant and imaginary part of dielectric constant decreases.