Origin of deep levels in the depletion region of p-ZnTe/n+-CdTe heterojunction determined by DLTS

Abstract

Deep level transient spectroscopy (DLTS) studies of the depletion region of p-ZnTe/n+-CdTe heterojunction have been done. Three deep hole trap levels were observed: one with activation energy of 0.14 eV (L1), another with 0.98 eV (L3), and the rest (L2) show a complex behavior possibly resulting from a continuous distribution of states occupying a certain width of energy level rather than a discrete one. The origin of these three levels have also been studied. From the bias-dependent DLTS, DLTS of heat treated samples, and DLTS of a p/n+ CdTe homojunction, it has been inferred that the trap level L1 is due to a thermal effect of the ZnTe film, L3 is due to a state in the ZnTe side of junction, and the complex L2 is due to the interface states resulting from dangling bonds caused by lattice mismatch.