Accumulation of Arsenic Implantation-Induced Donor Defects in Hg_0.7Cd_0.3Te Heteroepitaxial Structures

Accumulation of arsenic implantation-induced donor defects in heteroepitaxial Hg_1−xCd_xTe structures with the composition of the active layer x_a = 0.30 was studied with the use of the Hall-effect measurements and mobility spectrum analysis. The studies allowed for identifying the carriers in the implantation-damaged n⁺-layer, namely, electrons with low and intermediate mobility, and for establishing the dependence of their concentration on the ion fluence. The electrically active implantation-induced defects in the studied structures, similar to the case of those with x_a = 0.22, were identified as atoms of interstitial mercury captured by dislocation loops and quasi-point defects. In the material with x_a = 0.30, a weak dependence of the concentration of low-mobility electrons on the fluence was observed. In general, a substantial difference in the properties of p⁺–n junctions formed as a result of arsenic implantation in the structures with x_a = 0.30 and x_a = 0.22 was established. The difference was explained by the effect of the graded-gap surface layer on the diffusion of charged defects released during the implantation.