LAUSR

Three types of nBn structures based on mercury cadmium telluride grown by molecular beam epitaxy have been fabricated. As barrier layers in nBn structures, Hg1–xCdxTe at x = 0.67 and 0.84 and the 18 period Hg0.20Cd0.80Te (9 nm) – HgTe (2 nm) superlattice were used. To study the properties of barrier layers based on nBn structures, MIS devices were created using dielectric Al2O3 films. The impedance of the created devices was investigated over wide ranges of voltages, frequencies, and temperatures. Equivalent circuits of MIS devices based on nBn structures in the accumulation mode are proposed. It is shown that measurements of the frequency dependences of the impedance make it possible to determine the values of the differential resistance of the barrier layer in a wide range of conditions. It was found that the values of the differential resistance are determined only by the bulk component of the dark current, and the surface leakage component does not affect the measured impedance of MIS devices. The dependences of the values of the equivalent circuit elements on the area of structures, voltage, and temperature are determined. It is shown that in the temperature range 210–300 K, the values of the differential resistance of the barrier layer based on Hg0.33Cd0.67Te are determined by the diffusion-limited flow of holes from the contact and absorbing layers, at the forward and reverse biases, respectively. The values of the product of the differential resistance and the area are determined for nBn structures with various parameters of the barrier layers. The possibilities of using the measurements of impedance of MIS devices based on nBn structures to study the homogeneity of properties of various layers are demonstrated..