Electrical properties of ZnTe-ZnSe heterostructures

ZnTe-ZnSe heterostructures obtained by vacuum epitaxy under various thermal conditions have been studied. The results of structural investigations and also the dependences of the current-voltage and capacitance-voltage characteristics on the layer growth conditions are described.

The electrical properties of heterojunctions obtained at substrate temperatures of 300°–500°C, i.e. when the ZnTe or ZnSe formed single-crystal films, have been investigated. It is shown that in forward biased heterojunctions the current flow may be described by the tunnel-recombination mechanism of Riben and Feucht. The soft breakdown observed in reverse biased heterojunctions is caused by impact ionization. The capacitance measurements indicate that the effective number of charged interface states is approximately 10¹²-10¹³ cm^-2. The band diagram of the ZnTe-ZnSe heterojunction is proposed.