Structural studies of ZnS:Cu (5 at %) nanocomposites in porous Al$_{2}$O$_{3}$ of different thicknesses

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 $\mu$m. 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 (Cu$_2$S 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 $\mu$m, most copper atoms form the Cu$_2$S compound, while, in the sample deposited onto a 1-$\mu$m-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-$\mu$m-thick porous Al$_{2}$O$_{3}$ layer; this distance is smaller than in the other samples.