Investigation of the nucleation and growth of thin-film phosphors

The deposition of CaGa2S4:Ce has been accomplished using a commercial Liquid delivery system on two substrate surfaces: ZnS and SrS. However, the film deposited on ZnS was not of satisfactory quality because of the formation of an amorphous layer and a high amount of residual porosity within the deposition. The use of a SrS layer on top of the ZnS improved the nucleation by reducing the interfacial energy between the substrate and deposition. It greatly reduced the porosity in the coating and reduced the formation of the amorphous layer. The crystallinity of the CaGa2S4 400 peak was also increased by a factor of ten when a layer of SrS was used. Further, FWHM of the 400 peaks from the two depositions was not significantly different, indicating that the crystallite size and strain was approximately the same. The B-40 was increased by a factor of two, from 1.84 cd/m(2) for ZnS to 3.67 cd/m(2) for SrS. This increase is an improvement in the performance of the films and is attributable to the increase in the crystallinity.