Modification of chemically deposited ZnSe thin films by ion exchange reaction with copper ions in solution

The modification of chemically deposited ZnSe thin films of ∼ 0.3 μm thickness by ion exchange in dilute solutions 0.001 M–0.025 M of CuCl 2 has been investigated. The ion exchange reaction, as studied by XPS depth profile analysis, shows Cu/Zn ratios of 0.32 and 90 for a 90 s ion exchange in 0.001 M CuCl 2 and a 3 min ion exchange in 0.01 M CuCl 2, respectively. Following ion exchange, the binding energies are measured as 952 eV for Cu 2p 1 2 , 932 eV for Cu 2p 3 2 and 54.5 eV for Se 3d 5 2 . The corresponding values for CuSe thin film deposited directly from a chemical bath are 952, 932.5 and 55 eV. Optical transmittance spectra and sheet resistance measurements of the ion-exchanged films compare favourably with directly deposited CuSe thin films, which indicates the formation of CuSe. These results demonstrate that thin films of semiconducting materials can be prepared in a simple manner by ion exchange.