Admittance of metal-insulator-semiconductor structures based on graded-gap HgCdTe grown by molecular-beam epitaxy on GaAs substrates

Metal–insulator–semiconductor structures based on n-Hg1−xCdxTe (x = 0.19–0.25) were grown by molecular-beam epitaxy on the GaAs (0 1 3) substrates. Near-surface graded-gap layers with high CdTe content were formed on both sides of the epitaxial HgCdTe. Admittance of these structures was studied experimentally in a wide temperature range (8–150) K. It is shown that an increase in the composition of the working layer and a decrease in temperature lead to a decrease in the frequency of transition to high-frequency behavior of the capacitance–voltage characteristics. The differential resistance of space charge region in the strong inversion increases with the composition of the working layer and for x = 0.22 and 0.25, the differential resistance is limited by the Shockley-Read generation. The values of the differential resistance of space charge region at different frequencies and temperatures were found