Photoluminescence dependence on imposing bias for ZnGa2O4 and ZnGa2O4 activated with Mn2+ or Cr3+ n-type semiconductor electrodes

Photoluminescence (PL) dependence was investigated by imposing cathodic and anodic bias for ZnGa2O4, ZnGa2O4:Mn and ZnGa2O4:Cr n-type semiconductor electrodes. Under the cathodic bias PL intensity was weak at about 1/3 times compared with imposing no bias, while under the anodic bias the intensity was strong at about 2 times maximally by using the ZnGa2O4:Mn and ZnGa2O4:Cr electrodes although no change about the intensity was observed by using the ZnGa2O4 electrode. These results suggest that the emission attributed to recombination between electrons and holes is decreased by flow of cathodic current under the cathodic bias while the emission is increased to decrease at non-radiative transition rates under the anodic bias when the energy relaxation occurs.