Extended deep-level defects in MBE-grown p-type CdTe layers



Five deep-level hole traps, associated with native defects, have been revealed by means of deep-level transient spectroscopy in p-type CdTe layers grown on highly mismatched GaAs substrate by the molecular-beam epitaxy technique. Two of the traps have been attributed to the electronic states of dislocations on the ground of the logarithmic capture kinetics for capture of holes into the traps states. The images taken by transmission electron microscopy show that they are probably threading dislocations of 60°-type, generated at the mismatched interface with the substrate. One trap, which was observed only when the investigated space charge region was close to the metal–semiconductor interface, has been assigned to surface defect states. The last two traps, displaying exponential capture kinetics, have been ascribed to native point defects: the Cd vacancy and a complex formed of Cd vacancy and Te antisite, produced during the epitaxial growth of the CdTe layers. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)