Abstract
The origin and nature of star-shaped prismatic punching defects (PPDs) were analyzed by white-beam X-ray diffraction topography (WBXDT) and photoluminescence (PL) measurements. PPDs were observed in CdTe-based compounds that had Te-rich secondary phase defects and were annealed only under Cd overpressure.
The evolutional features of the PPDs during annealing were similar to those of a diffusion process, that is, the in-diffusion of Cd vapor via Cd vacancies. PL mapping around the PPDs reveals that the stoichiometry of PPDs is the same as that of a normal matrix, and that PPDs are just structural defects with non-radiative emission induced by the exothermic reaction between Cd and Te.
We find that Te-rich secondary phase defects can be removed without the generation of star-shaped PPDs, if the exothermic reaction rate can be slowed down to reduce the thermal gradient between the Te-rich region and the surrounding matrix. (C) 2013 Elsevier B.V. All rights reserved