The effect of ZnS content on the luminescence and electrical properties of ZnO : Zn phosphor

Abstract

Zinc oxide phosphors (ZnO : Zn) were prepared by solid state sintering of ZnO powders with ZnS and screen printed onto ITO-coated glass substrate. The effect of ZnS content and sintering temperature on the cathodoluminescence brightness, efficiency and electrical properties of ZnO : Zn were studied. Samples with 5 wt % ZnS and sintered at 1100 degreesC exhibit the highest brightness and efficiency among all the compositions studied. The brightness of phosphors increases linearly as the accelerating voltage V and/or beam current I increases. While the efficiency decreases initially and then reaches a constant value as V and/or I increases. Both the conductivity sigma and carrier concentration n of the phosphor increase with the increase of ZnS content in the starting composition. Results of Hall measurement suggest that the ZnO : Zn phosphor is an n-type conductor with an electron mobility of around 175cm(2)/V-s. For specimen with 5 wt % ZnS, both sigma and n increases initially with the increase of sintering temperature T, and reaches a constant value at T greater than or equal to 1000 degreesC. The unreacted ZnS found in samples sintered at T < 1000 degreesC explains the temperature dependence of sigma and n. (C) 2002 Kluwer Academic Publishers.