THE GROWTH AND STRUCTURE OF SHORT-PERIOD (001) HG1-XCDXTE-HGTE SUPERLATTICES

Molecular beam epitaxially grown short period (001) Hg1-xCdxTe-HgTe superlattices have been systematically investigated. Several narrow well widths were chosen, e.g., 30, 35 and 40 angstrom, and the barrier widths were varied between 24 and 90 angstrom for a particular well width. Both the well width and the total period were determined directly by means of x-ray diffraction. The well width was determined by exploiting the high reflectivity from HgTe and the low reflectivity from CdTe for the (002) Bragg reflection. Knowing the well and barrier widths we have been able to set an upper limit on the average Cd concentration of the barriers, x(b)BAR, by annealing several superlattices and then measuring the composition of the resulting alloy. x(b)BAR was shown to decrease exponentially with decreasing barrier width. The structure of a very short period superlattice, i.e., 31.4 angstrom, was also investigated by transmission electron microscopy, corroborating the x-ray diffraction results.