Electroluminescence studies of chemically deposited (Zn-Cd)S:Cu,F films

Abstract

Electroluminescence (EL) emission has been observed under AC field excitation in chemically deposited (dipping technique) films of (Zn-Cd)S:Cu,F using substrates of conducting glass plates. Results of XRD, SEM, absorption spectra, transmission spectra, EL emission spectra, voltage, frequency and temperature dependence and brightness waves of EL brightness are presented and discussed. SEM studies show better growth condition in presence of F. X-ray diffraction studies show diffraction lines due to CdS and ZnS. Both the studies represent average particle sizes of the order of 1A. Absorption studies show change in band gap due to increasing concentration of ZnS. The observed EL emission (blue-green region) may be due to Cu, F combination. Results of transmission spectra give band gap similar to those given by absorption spectra. From voltage dependence of EL brightness acceleration-collision mechanism is found to be effective. Frequency dependence of EL brightness shows first an increase in brightness in the lower frequency range followed by saturation at higher frequencies. Temperature dependence of EL emission shows a maximum at 40°C. Brightness waves consist of primary and secondary waves, which depend on voltage and frequency of excitation & the ambient temperature. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)