Optimum growth conditions of polycrystalline ZnTe

Abstract

ZnTe which has been the object of considerable study in the past ten years, because of its properties that make it a suitable material for opto-electric devices. ZnTe crystallizes with a zincblende structure, and has a direct energy gap of 2.26 − 2.5eV, depending on the dopant used.
Most studies indicate that it is unavoidably Te-rich, which leads to a p-type conductivity unlike other II-VI compounds. This material exhibits many interesting solid state phenomena and electro-optical effects of practical importance. Some examples are found in electroluminescence, image intensification and storage, photovoltaic effect, field effect transistors and solar cells.
Among the different techniques that have been used to prepare this material are the resistance heater method used by Fischer and the vapor phase growth technique used by Kikuma, et al. Kobayashi, et al., fabricated ZnTe doped with Cu using epitaxial growth on glass substrates. Takemura, et al., prepared ZnTe by means of MBE on GaAs substrates. Tokumitsu, et al., used RF sputtering technique. Duddles, et al., prepared ZnTe:N grown by MBE.
Most of the techniques used for preparing ZnTe need complex, sophisticated equipment, which do not in general yield ZnTe crystals in large quantities. In this study, we attempt to grow ZnTe crystals by unseeded vapor deposition and characterize the samples so prepared.