Acceptor levels in GaSe:In crystals investigated by deep-level transient spectroscopy and photoluminescence

Abstract

Deep-acceptor levels associated with indium in indium-doped GaSe crystals have been measured. High-quality Schottky diodes of GaSe:In have been fabricated and characterized using current-voltage, capacitance-voltage, and deep-level transient spectroscopy (DLTS). Four DLTS peaks at 127, 160, 248, and 319 K, corresponding to 0.21, 0.22, 0.44, and 0.74 eV above the valence band, were well resolved and assigned to be an indium-on-gallium antisite (InGa), a gallium vacancy (VGa), an indium gallium vacancy complex (VGa -In), and a native defect associated with stacking fault or dislocation, respectively. Low-temperature photoluminescence (PL) spectroscopy measure-ments were performed on GaSe and GaSe:In crystals. The ground and the first excited states of the free exciton emissions were identified and the band-gap energies were determined. The results that the peak of exciton bound to acceptor (A0,X) disappeared and the peak of donor-acceptor pair appeared in GaSe crystal after indium doping are consistent with the DLTS acceptor assignments. © 2008 American Institute of Physics.