STRUCTURAL STUDIES OF AMORPHOUS ZN-P FILMS

Large angle X-ray diffraction studies were performed on vapour deposited Zn-P amorphous films with phosphorus contents of 43, 50 and 68 at %. Using MoK-alpha radiation, measurements have been made for 4-pi sin theta/lambda between 0.06 and 1.6 nm-1. The experimental method and data reduction procedure are described. The structure of the amorphous Zn-P films is analysed using both intensity and radial distribution functions. The experimental results are compared with a number of paracrystalline models based on various crystalline polymorphs of the II-V system. Comparison shows that reasonable agreement is achieved for distorted tetrahedral structures: the intermediate between CdAs and Si type III for Zn57P43 and Zn50P50 and the distorted CdAS2 for Zn32P68. The sizes of the microparacrystals are evaluated from the integral widths of the first diffraction peaks and the lattice distortions by applying paracrystalline theory. It is shown that the size of the microparacrystal and the degree of the lattice distortion are correlated by the alpha* relation for the investigated Zn-P amorphous films.