Structural studies of ZnS:Cu (5 at %) nanocomposites in porous Al2O3 of different thicknesses

Abstract

We present EXAFS, XANES, and X-ray diffraction data on nanoscale ZnS:Cu (5 at %) structures fabricated by the thermal deposition of a ZnS and Cu powder mixture in porous anodic alumina matrices with a pore diameter of 80 nm and thicknesses of 1, 3, and 5 μm. The results obtained are compared with data on ZnS:Cu films deposited onto a polycor surface. According to X-ray diffraction data, the samples contain copper and zinc compounds with sulfur (Cu₂S and ZnS, respectively); the ZnS compound is in the cubic (sphalerite) and hexagonal (wurtzite) modifications. EXAFS and XANES studies at the K absorption edges of zinc and copper showed that, in samples deposited onto polycor and alumina with thicknesses of 3 and 5 μm, most copper atoms form the Cu₂S compound, while, in the sample deposited onto a 1-μm-thick alumina layer, copper atoms form metallic particles on the sample surface. Copper crystals affect the Zn–S interatomic distance in the sample with a 1-μm-thick porous Al₂O₃ layer; this distance is smaller than in the other samples.