Nano-size defect layers in arsenic-implanted and annealed HgCdTe epitaxial films studied with transmission electron microscopy

Optical reflectance and bright-field and high-resolution transmission electron microscopy studies of radiation damage induced by implantation of arsenic ions with 190 keV and 350 keV energy and 1014 cm–2 fluence in molecular-beam epitaxy-grown Hg0.7Cd0.3Te films were performed. A similarity in defect pattern formed by arsenic implantation in Hg1−xCdxTe with x ≈ 0.2 and x ≈ 0.3 straight after the implantation was observed with formation of three nano-size defect layers containing dislocation loops of vacancy- and interstitial-types, single dislocations and lattice deformations. After post-implantation arsenic activation annealing, most of these defects in our Hg0.7Cd0.3Te films, in contrast to Hg0.8Cd0.2Te films, disappeared. This effect is explained by the reduced influence of the electric field of the graded-gap surface layer on the diffusion of charged point defects under annealing.