Mechanisms of CdTe(100) sublimation

Abstract

The results of accelerated molecular dynamics and energetics calculations of the binding energies, barriers, and prefactors for various stages of desorption from the Cd-terminated and (2 × 1) Te-terminated surfaces of CdTe(100) are presented. Our results indicate that while the desorption barriers for Te2 on the Cd-terminated (100) surface are quite large, the corresponding prefactors are also extremely large. As a result, Cd desorption is the rate-limiting step for the case of sublimation via vacancy pit nucleation and growth, while the corresponding desorption barriers are in good agreement with the effective activation energy obtained in experiments for T>360∘C. A detailed analysis which takes into account our results for the Cd and Te2 desorption rates also leads to good quantitative agreement with the experimentally determined sublimation rate over this temperature range. In contrast, our results indicate that for T<360∘C the desorption of isolated Cd atoms on the (2×1) Te-terminated surface may play an important role. The corresponding desorption barrier (Ed≃1.4 eV) is close to that found experimentally over this temperature range.