A study on correlation of low voltage cathodoluminescent properties with electrical conductivity of In2O3-coated ZnGa2O4 : Mn phosphors

Abstract

The mechanism of enhancement on the low voltage cathodoluminescence (CL) efficiency by addition of In2O3 in the phosphor particles has been investigated. The effect of In2O3 coating by the sol-gel method on the CL of ZnGa2O4:Mn phosphors improves the luminance of low voltage CL noticeably. Especially it is observed that the emission intensity for the phosphor ZnGa2O4:Mn coated with 2 wt % In2O3 is about four times higher than the as-it-is (non-coated In2O3). Contrary to low voltage CL, the photoluminescence intensity of In2O3-coated ZnGa2O4:Mn phosphors decreases with an increase in In2O3 coating wt %. It is shown by Rutherford backscattering study that the surface distribution of In2O3 on In2O3-coated ZnGa2O4:Mn phosphors is islandlike but not intermediate-like (islands on a uniform layer). Also, investigations performed on the electrical conductivity of the phosphor screen prove the In2O3-coated ZnGa2O4:Mn phosphor screen to be an insulator. From the present work, it is understood that In2O3 in the phosphor particles probably act as the localized bridge in draining the accumulated charge on the phosphor surface down to the indium tin oxide substrate due to the formation of the localized electrically conductive channels. (C) 2000 The Electrochemical Society. S0013-4651(00)03-138-4. All rights reserved.