Enhanced ultraviolet photoconductivity in semiconducting ZnGa2O4 thin films

Abstract

We have investigated the conductivity and photoconductivity response of undoped and Li-doped ZnGa2O4 epitaxial films grown using pulsed-laser deposition. A significant enhancement of the ultraviolet (UV) photoresponse is observed with Li doping that also correlates with an enhanced luminescent intensity. The wavelength dependence observed for creation of free carriers under UV excitation suggests that the transition is either band-to-band or involves a defect level near the band edge. Moderate n-type dark conductivity is observed for undoped films processed under reducing conditions. With Li doping, dark conductivity is reduced, suggesting that lithium ions in the zinc gallate lattice serve as deep acceptors. In addition, Li doping effectively eliminates persistent photoconductivity that is commonly observed in undoped films, suggesting the possible use of Li-doped ZnGa2O4 as a visible wavelength blind UV photodetector.

Enhancement of photoluminescence, persistent luminescence and photocatalytic activity in ZnGa2O4 phosphors by lithium ion doping

“…Zinc gallate (ZnGa 2 O 4 ) phosphor has attracted enormous attention recently, because ZnGa 2 O 4 is an attractive phosphor host candidate material for vacuum florescent displays and electroluminescence displays due to its favorable cathodoluminescence (CL) and photoluminescence (PL) properties, and thermal stability [1,2]. With a band gap of 4.4 eV, ZnGa 2 O 4 exhibits a blue luminescence under excitation by low voltage electrons (30 V d.c) or ultraviolet light [3].…”

Ultraviolet/orange bicolor electroluminescence from an n-ZnO/n-GaN isotype heterojunction light emitting diode

“…1(d)shows the SAED pattern of the interface, from which the interfacial layer was identified as a cubic structural ZnGa 2 O 4 layer, ½101 c ==½1 210 h , with the hexagonal wurtzite structrual ZnO and GaN. The ZnGa 2 O 4 was characterized as a wider band gap material (with a band gap of 4.4-5.0 eV) than those of ZnO and GaN according to literature reports 12,19. The forming of ZnGa 2 O 4 revealed that some defects like oxygen vacancies (V O ) or gallium vacancies (V Ga ) should be introduced to ZnO or GaN especially near the interfacial layer during the thermal annealing.…”

Elastic, phonon and thermodynamic properties of ZnAl2O4 and ZnAl2S4 compounds from first–principles calculations

“…Compounds in this family usually have wide band gaps and are attractive in theory and experiments for better understanding of their physical properties [1][2][3][4]. In the normal spinel with cubic symmetry (space group Fd-3m), the A atoms occupy the center of tetrahedral sites and the B atoms occupy the center of octahedral sites.…”