Micro-photoluminescence spectroscopy at variable temperature, excitation
intensity and energy was performed on a single InAs/AlAs self-assembled quantum
dot. The exciton emission line (zero-phonon line, ZPL) exhibits a broad
sideband due to exciton-acoustic phonon coupling by the deformation potential
mechanism. Additionally, narrow low-energy sidebands at about 0.25 meV of the
ZPL are attributed to exciton-acoustic phonon piezoelectric coupling. In
lowering the excitation energy or intensity these bands gradually dominate the
emission spectrum of the quantum dot while the ZPL disappears. At high
excitation intensity the sidebands due to piezoelectric coupling decrease
strongly and the ZPL dominates the spectrum as a consequence of screening of
the piezoelectric coupling by the photocreated free carriers.Comment: 4 pages, 4 figure