A radio-tracer technique was used to measure Hg self-diffusion in bulk and liquid-phase epitaxial Hg1-xCdxTe. A high-resolution sectioning technique permitted the profiling of thin epitaxial layers in sub-micron steps. Samples with x-values of between 0.16 and 0.23 were isothermally annealed at temperatures of between 300 and 400C, and Hg reservoirs which contained 203Hg were used as vapor sources. There were indications that 2 components existed in the radio-tracer profiles of both bulk and epitaxial material. In some cases, it was possible to deduce diffusion coefficients, D1 and D2, for the near-surface and deeply penetrating components, respectively. In the case of bulk material which had been annealed at 400C under a saturated Hg pressure, D1 was equal to 2.0 x 10-12cm2/s and D2 was equal to 1.1 x 10-11cm2/s. The diffusion coefficients at 310C under a saturated Hg pressure were determined in both bulk and epitaxial material. Close agreement was found between these results, with an average value of 1.4 x 10-13cm2/s for D1. It was suggested that this was the first time that radio-tracer results had been reported for epitaxial material. The present data, when combined with literature results, indicated a possible change in the activation energy for Hg diffusion at about 350C. This was attributed to a change in the predominant diffusion mechanism.

N.Archer, H.Palfrey: Journal of Electronic Materials, 1991, 20[6], 419-24