Admittance of metal-insulator-semiconductor devices based on HgCdTe nBn structures

Metal-insulator-semiconductor (MIS) structures were fabricated by depositing an Al2O3 dielectric on top of the contact layer of a mid-wave infrared nBn detector based on n-Hg1-xCdxTe grown by molecular beam epitaxy on GaAs (013) substrates. It is shown that when creating a backward electrode on the absorbing layer, the form of the capacitance-voltage characteristics depends not only on the properties of the contact layer, but also on the properties of the barrier and absorbing layers. An equivalent circuit of MIS structure based on nBn detector with mesa configuration is proposed. It is shown that measurements of the admittance of MIS structures with mesa configuration allow one to study the properties of the barrier layer in the nBn structure. The influence of infrared radiation on the temperature dependence of the barrier layer resistance is studied.