Investigation of the Differential Resistance of MIS Structures Based on n-Hg_0.78Cd_0.22Te with Near-Surface Graded-Gap Layers

Abstract—

The admittance of MIS structures based on n(p)-Hg_1–xCd_xTe (x = 0.21–0.23) grown by molecular-beam epitaxy on Si and GaAs substrates is studied. The possibility of increasing the value of the product of the differential resistance of the space charge region and area of the field electrode R_SCRA by creating near-surface graded-gap layers with an increased content of CdTe is investigated. It has been established that the creation of a graded-gap layer leads to an increase in the value of R_SCRA by a factor of 10–200 for MIS structures based on n-Hg_0.78Cd_0.22Te due to suppression of tunneling generation through deep levels and a decrease in the Shockley–Read current. MIS structures based on n-Hg_0.78Cd_0.22Te without a graded-gap layer grown on GaAs substrates have R_SCRA values that exceed 10 or more times the values of the same parameter for structures grown on Si substrates.