Photoelectric properties of metal–insulator–semiconductor structures based on HgCdTe nBn with a superlattice in the barrier region

Subject of study. The feasibility of applying superlattices as barrier layers in unipolar barrier nBn structures based on n-type HgCdTe [grown by molecular beam epitaxy (MBE)] for photodetection is investigated. Aim of study. This study aims to determine the influence of infrared optical radiation on the electrophysical characteristics of nBn structures based on HgCdTe (grown by MBE) with a superlattice in the barrier region. Method . Epitaxial Hg 1− x Cd x Te films, constituting nBn structures with a superlattice composed of 18 periods of Hg 0.2 Cd 0.8 Te (9 nm) and HgTe (2 nm), were grown by MBE. These films were then used to fabricate metal–insulator–semiconductor (MIS) structures. The photoelectric properties were investigated using admittance spectroscopy, both with and without 940-nm infrared light-emitting diode (LED) irradiation. Main results. Infrared optical radiation evidently affects the electrophysical characteristics of nBn structures based on HgCdTe (grown by MBE) with a superlattice in the barrier region. However, this influence does not mirror the behavior of classical MIS structures exposed to optical radiation, indicating that the superlattice contributes to the photoelectric properties of the studied structures. The observed effects are likely related to the recharging of energy levels (minibands) in the superlattice within the barrier region of the nBn structure. Practical significance. Since the application of superlattices in barrier nBn structures based on n-type HgCdTe is considered the most promising approach to eliminating the potential barrier for minority charge carriers, the results of this study may provide a foundation for developing photosensitive structure designs for the mid- and long-wave infrared ranges and for the subsequent creation of photodetector elements.