Effect of the barrier width on the cathodoluminescence spectra in the strained CdTe/ZnTe superlattices with quantum dot layers

Abstract

The influence of the ZnTe barrier width on the cathodoluminescence (CL) spectra of the CdTe/ZnTe superlattices (SL) with CdTe quantum dots (QD) is studied. For the samples with the barrier width of 100, 50 and 25 ml CL spectra consist only of a single band with maximum at E = 2.03‐2.01 eV at 80 K. We assign this band to the emission from QD ensemble. For the samples with 10 ml barrier width the emission band splits into two lines of different intensity with maxima at E = 2.01 and 1.95 eV. However the emission spectrum of SL with 5 ml barrier width consists also of only one band with maximum at E = 1.92 eV. We explain these results by the influence of biaxial strain, resulting from the lattice mismatch, on the ground state of the heavy‐hole and light‐hole subbands in CdTe and ZnTe layers. For the CdTe/ZnTe SL with the deposited CdTe layer thickness of 1.5 ml we observed equidistant lines in QD and wetting layer emission bands separated by CdTe 2LO phonon energy (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)