Optical quenching mechanism in InAs quantum dots in an Al0.95Ga0.05As matrix

Abstract

InAs quantum dots (QDs) were grown grown in an Al0.95Ga0.05As matrix by using the molecularbeam epitaxy technique. Photoluminescence (PL) measurements were made as functions of the magnetic fields and the temperature. Two prominent PL transitions were observed from QDs and defects in the matrix layer at 5 K. In magnetic fields, the transition from QDs does not change its spectral shape at magnetic fields up to 15 T, whereas the defect-related transition shows a blue-shift at magnetic fields above 8 T. By varying the temperature from 5 K to room temperature, the transition from QDs persists up to similar to 200 K and the defects-related transition quenches quickly near 70 K. The activation energies obtained by using an Arrhenius fitting of the PL intensities indicate that the excitons dissociated by thermal energy transfer into higher energy levels.