Realization of both p- and n-type conduction for ZnSe-ZnTe strained-layer superlattices

The conduction types of ZnSe-ZnTe strained-layer superlattices (SLS's) have been controlled by using the modulation doping technique. Two kinds of modulation-doped SLS's were prepared. One of them consisted of gallium (Ga) doped ZnSe layers and undoped ZnTe layers. The other consisted of undoped ZnSe layers and antimony (Sb) doped ZnTe layers. The conduction types of the samples modulation doped with Ga and Sb were shown to be n and p type, respectively whereas the undoped samples exhibited n-type conduction. The electrical properties of the undoped and modulation-doped samples were evaluated by the van der Pauw method. The carrier concentrations of all types of samples were about 5×10¹³/cm³ at room temperature. The temperature dependence of the electrical properties was measured for an undoped sample and a sample modulation doped with Sb. The carrier concentrations increased with temperature and reached about 1×10^{1 7}/cm³ at 500 K.