Self-Induced Persistent Photoconductivity in ZnTe-Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te$\text{}_{1-y}$Se$\text{}_{y}$ Heterojunctions

At temperatures lower than 200 K the photomemory effect has been observed in ZnTe-Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te$\text{}_{1-y}$Se$\text{}_{y}$ heterojunctions. The persistent photoconductivity can be achieved either by illumination from an external light source or by a self-absorption of the electroluminescence radiation when a voltage of about 10 V for a few seconds is applied to the diode. Current-voltage characteristics are of the form I~ V$\text{}^{m}$. The capacitance and electroluminescence measurements show that the photomemory effect in ZnTe-Cd$\text{}_{1-x}$Mn$\text{}_{x}$ Te$\text{}_{1-y}$Se$\text{}_{y}$ heterojunctions can be caused by the bistable nature of the In dopant in the Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te$\text{}_{1-y}$Se$\text{}_{y}$ substrate. In the high resistivity interface layer and the substrate material indium forms centers similar to DX-like centers in Zn$\text{}_{x}$Cd$\text{}_{1-x}$Te and Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te.