Observation of Hg diffusion in CdTe by means of 40-MeV O5+ ion backscattering

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Abstract
The diffusion profile of Hg in CdTe crystals was observed by means of heavy ion (40 MeV O5+) backscattering. The near‐surface region of CdTe immersed in Hg was investigated up to 1.4 μm from the surface. The observed Hg profile indicated that the concentration of Hg atom at the surface reached 4×1020 cm−3 and the distribution was interpreted by a simple diffusion model. Temperature dependence of the diffusion coefficient was determined to be D=5×103 exp[(−2.0±0.3) eV/kT] (cm2/s). In the case of CdTe immersed in Hg which contained a small amount of Cd, it was found that Hg diffusion did not occur. These experimental facts suggest that the rate of Hg diffusion is controlled by the diffusion of a Cd vacancy which is introduced by the outdiffusion of Cd atoms from CdTe crystals.