Simultaneous layer-by-layer and step-flow sublimation on the CdTe(001) surface derived from a diffraction analysis

High-resolution low-energy electron diffraction (HRLEED), mass spectrometry , and computer simulations using a solid-on-solid model were combined to st udy the sublimation kinetics of the CdTe(001) surface. The HRLEED spot prof ile measurements show that specular spot intensity oscillations during subl imation are caused by an only small variation (similar to 15%) of the step density, and that the step flow contribution dominates the sublimation proc ess. Consequently, two different activation energies were derived from the mass desorption (1.55 eV) and the oscillation frequency of the HRLEED inten sity (1.94 eV). These findings are confirmed by computer simulations of the sublimation on irregularly stepped surfaces. These show a mixed sublimatio n mode with vacancy nucleation (leading to intensity oscillations) only on the largest terraces and step flow otherwise. On the basis of these results , we can explain discrepancies in earlier determined sublimation energies.