ABSORPTION AND BAND STRUCTURE MODIFICATION IN BORON-SUBSTITUTED GaSe

Single crystals Ga 1-x B x Se (x = 0.3 and 0.5%) were synthesized using the horizontal Bridgman method, and their optical characteristics were systematically examined.UV-Vis absorption spectra revealed a direct band gap of 1.960-1.963eV, slightly narrower than that of undoped GaSe (≈ 2.0 eV).This reduction originates from lattice distortions and electronic perturbations introduced by boron atoms, which shift the absorption edge toward longer wavelengths, improving the material's suitability for visible and near-infrared photodetection.Additional absorption features at 1.05 eV and 1.35 eV correspond to boron-induced impurity states that affect the temperature dependence of absorption.At lower boron concentrations, the absorption coefficient increases with temperature due to thermal excitation, while at higher concentrations, a negative temperature coefficient appears, indicating enhanced radiative recombination.These results demonstrate that controlled boron incorporation effectively tailors the band structure and optical response of GaSe, enabling its application in broadband optoelectronic and photodetector devices.