Admittance Characteristics of nBn Structures Based on Hgcdte Grown by Molecular Beam Epitaxy

Abstract

For the first time, the admittance of nBn structures based on HgCdTe grown by molecular beam epitaxy was experimentally investigated in a wide range of frequencies and temperatures. The CdTe content in the barrier layer of studied samples varied from 0.74 to 0.83, and the thickness of this layer was from 210 to 300 nm. The experimental frequency dependences of the admittance of nBn structures are in good agreement with the results of calculation by the equivalent circuit method. The proposed equivalent circuit consists of two seriesconnected chains, each of which contains a capacitance and a resistance connected in parallel. The change in the values of the equivalent circuit elements during heating from 9 to 300 K and under application of the bias voltage was studied. It is shown for the first time that illumination of nBn structures based on HgCdTe by radiation with a wavelength of 0.91 μm causes relaxation of values of the equivalent circuit parameters for hundreds of minutes after the illumination is turned off. Mechanisms of the equivalent circuit element formation, as well as peculiarities of the admittance dependences at various parameters of the barrier layers, are discussed.