Electrical properties and injection luminescence in ZnSe-ZnTe heterojunctions prepared by liquid-phase epitaxy

Abstract

The electrical properties and the injection electroluminescence in the ZnSe-ZnTe n-p heterojunctions prepared by the liquid-phase epitaxial growth from Zn or Bi solution have been studied. The prepared heterojunctions consist of a p-s-n structure with distributed trap centers at the boundary region. The heterodiodes show an emission band peaking at about 1.94–2.04 eV at room temperature. At 77 K, the spectra generally have four emission bands at 1.98, 2.32, 2.70, and 2.78 eV. The dominance of any one of these emission bands over the others depends upon the preparation conditions. The photoluminescence measurements of the heterojunctions show that the light generation of the heterodiode occurs at the ZnSe branch of the junction: The emission occurs through hole injection from the p-type ZnTe into the n-type ZnSe. The best value for the external quantum efficiency of the light emission in the heterodiodes measured by an integrating sphere method is about 4×10−3 photons per electron at 77 K. The relation between the luminescence and the electrical characteristics of the prepared heterodiodes is discussed with tentative band models.