Electrical and Optical Properties of GaSe-SnO₂Heterojunctions

Abstract

The capacitance-voltage (C-V) and forward biased current-voltage (I-V) characteristics, electroluminescence (E.L) and photovoltaic effect of GaSe–SnO2 heterojunction diodes are measured. SnO2 layer is deposited on the c-plane of GaSe by using the spray method. The C-V and I-V characteristics of these diodes reveal the existence of a high resistivity layer, probably due to the diffusion of Sn into GaSe. The width of this layer is about 2.6 µm. And the current transport mechanism at low voltage is space-charge-limited. The trap density and the energy level of the trap from the valence band estimated by Lampert theory are about 5×1013∼1×1014 cm-3 and 0.4∼0.6 eV, respectively. The electroluminescence spectra at 275 K show one emission band due to free exciton recombination.