Interdiffusion in HgTe–CdTe superlattices

Semiconductor superlattices comprised of alternating HgTe and CdTe layers have been proposed as a tunable narrow band gap semiconductor for long wavelength optoelectronic applications. Growth of this novel superlattice material has been reported by several laboratories. Its usefulness as a narrow band gap optical material, however, has not been established. A main issue of concern is the interdiffusion of the constituent Hg, Cd, and Te atoms across the heterointerfaces of the superlattice structure. To determine the extent of this interdiffusion we have carried out, for the first time, temperature dependent x‐ray diffraction measurements on HgTe–CdTe superlattices. Peak intensities of the superlattice satellites were monitored as a function of annealing temperature and time to yield estimates of the interdiffusion coefficient D(T). Our results indicate there is appreciable intermixing of the HgTe and CdTe layers at temperatures as low as 110 °C. Such results have serious implications for the use of this material in optoelectronic devices.