Metal–insulator–semiconductor properties of HgTe–CdTe superlattices

Abstract

We report here the first metal–insulator–semiconductor (MIS) measurements of HgTe–CdTe superlattices. MIS measurements were made on two n‐type superlattices grown on (001) CdZnTe and (112)Cd CdTe substrates and on a (p) HgTe–CdTe superlattice on an (n) mercury cadmium telluride (MCT) (x=0.25) heterostructure. The carrier concentrations for the superlattice layers are in the low to mid‐1015 cm−3 range. Storage time measurements indicate that the superlattices are dominated by generation recombination and interface currents for T > 130 K, while the heterostructure is dominated by thermal ionization of electrons across the conduction‐band barrier at the interface between the two layers, which we measure to be 110 mV. The breakdown electric fields as deduced from storage time measurements are very large for these superlattices (∼3×104 V/cm, equaling high‐quality bulk MCT) and are indicative of the large effective masses in the superlattice growth direction.