Improvement of the nucleation and growth of thin film phosphors for electroluminescent flat panel displays

摘要

The deposition of CaGa_2S_4:Ce has been accomplished using a commercial liquid delivery system on two substrate: 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 porosity in the coating and reduced the formation of the amorphous layer. The crystallinity of the CaGa_2S_4 400 peak was also increased by a factor of ten when a layer of SrS was used. Further, the 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 crystalinity. To utilize these improvements, the ability to deposit both the SrS and CaGa_2S_4:Ce layers within the same reactor has been developed.