An Experimental Study of the Dynamic Resistance in Surface Leakage Limited nBn Structures Based on HgCdTe Grown by Molecular Beam Epitaxy

Mid-wave infrared nBn structures based on HgCdTe grown by molecular beam epitaxy on GaAs (013) substrates were fabricated. The composition in the absorbing layer was 0.29, and in the barrier layer it was 0.67. It was shown that the dark currents of the created nBn structures are limited by the surface leakage component. To study the bulk component of the dark current, it was proposed to use the admittance measurements of test metal-insulator-semiconductor (MIS) devices based on fabricated nBn structures in the case of the formation of a backward contact to the absorbing layer. It was established that surface leakage does not affect the dynamic resistance of the MIS device barrier. The dependence of the dynamic resistance of the barrier layer (R_b) of the MIS device in the accumulation mode on the area of the front electrode (A), voltage, and temperature was determined. It was shown that, with the exclusion of surface leakage, the values of the R_bA product in a temperature range of 230–300 K at forward biases are determined by the diffusion current of holes from the contact layer, and at reverse biases, by the diffusion current from the absorbing layer. It was found that at temperatures of 210–300 K, R_bA values exceeding the values of this parameter determined according to the empirical model Rule 07 were realized in the fabricated structures.