GROWTH AND PROPERTIES OF CdSe THIN FILMS BY A NEW PROCESS OF ELECTROCHEMICAL SELENIZATION OF Cd METAL LAYERS

摘要

Growth and properties of cadmium selenide semiconductor thin films pre- pared by a new electrochemical selenization process (ECS) are described. The as-formed CdSe thin films have large (～l um) crystallites in hexagonal modification. The differential selenization kinetics in the intra- and intergrain regions causes the formation of stoichiometric CdSe film to be highly depen- dent on time. CdSe composition is independent of selenization parameters. Two direct optical band gaps at 2.09 and l.44 eV, as opposed to a single gap at l.7 eV, are observed in CdSe film selenized at 0.6 and 0.4 mA/cm~2 current densities, respectively. A mechanism of selenization based on Cd ionization by oxygen reduction and reaction with cathodically released Se ions is pro- posed for the CdSe film formation.