The diffusion and solubility of Cu in monocrystals was measured, at 200 to 400C, by using radiotracer and sectioning techniques. It was found that the diffusivity in this range could be described by the Arrhenius relationship:

D(cm2/s) = 6.65 x 10-5exp[-0.57(eV)/kT]

while the corresponding surface Cu concentration in diffused CdTe slices could be described by:

Co(/cm3) = 1.56 x 1023exp[-0.55(eV)/kT]

The addition of Cd or Te to the capsule did not result in profiles that were significantly different to those given by the above expressions, and it was suggested that diffusion probably occurred via a defect of the form: (CuiCuv)'. Most of the activation energy for diffusion was taken up by the formation of the defect rather than by its migration through the lattice. A much faster diffusion mechanism (some 100 times faster), which did not exhibit any consistent behavior as a function of temperature, was also detected in the diffusion profiles. It was concluded that, because of this, CdTe would not act as an effective barrier in the fabrication of HgCdTe infra-red detectors, and would not prevent Cu from diffusing from the substrate and through a CdTe buffer layer, into an epitaxially grown HgCdTe layer.

E.D.Jones, N.M.Stewart, J.B.Mullin: Journal of Crystal Growth, 1992, 117, 244-8