Dependence of the vacuum sublimation rate of CdTe upon crystallographic orientation

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Abstract
A study of the crystallographic orientation dependence of the vacuum sublimation rate of undoped (111) and (100) CdTe crystals was carried out in the temperature range 310–390 °C. A rate of sublimation as high as 580 Å/min was observed at 380 °C for the (111)Te face which was about 4 and 12 times higher than that of (111)Cd and (100) faces, respectively. The corresponding activation energies for sublimation of these faces were determined as 2.21, 1.79, and 1.54 eV. The differences and magnitudes of the sublimation rates decrease with decreasing temperature and at t≤310 °C the sublimation rate is less than 3 Å/min, independent of the crystallographic orientation. The surface morphology of sublimated samples reveals thermal etch pits which are specific for each studied face. In the case of (111)Cd and (100) faces, etch pit densities up to about 107 cm−2 were observed, which probably corresponds to the concentration of dislocations and other defects present in the studied samples.