The structural and optical properties of ten-stack InAs/GaAsSb quantum dots (QDs) with different spacer layer thicknesses (ds = 2, 5, 10, and 15 nm) are reported. X-ray diffraction analysis reveals that the strain relaxation of the GaAsSb spacers increases linearly from 0% to 67% with larger ds due to higher elastic stress between the spacer and GaAs matrix. In addition, the dislocation density in the spacers with ds = 10 nm is lowest as a result of reduced residual strain. The photoluminescence peak energy from the QDs does not change monotonically with increasing ds due to the competing effects of decreased compressive strain and weak electronic coupling of stacked QD layers. The QD structure with ds = 10 nm is demonstrated to have improved luminescence properties and higher carrier thermal stability.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)