AFM study of micromorphology and microscopic growth mechanisms of Hg₁₋x CdxTe LPE epitaxial layers

Abstract

Mercury cadmium telluride epitaxial layers exhibiting large areas with nearly atomically-flat surface were grown using liquid phase epitaxy (LPE) from Te-rich solution in closed system. Evolution of surface morphology during different steps of LPE growth was studied using scanning probe microscopy. Various growth features including monomolecular steps were observed. Both scanning probe microscopy (SPM) images and surface composition analysis with X-ray fluorescence spectroscopy clearly showed that vapor phase growth at the melt homogenization step contributed to epilayer formation and further evolution of its morphology. It was found that formation of flat areas proceeds via a dislocation-controlled monomolecular step growth mechanism. Phenomenological estimation of local supersaturation conditions giving rise to these areas was given on the basis of the interstep distance of the growth spirals originating from screw dislocations. The results obtained suggest the way of radical morphological improvement of the LPE-grown epilayers.