Micro-photoluminescence spectroscopy for varying temperature, excitation intensity and energy was performed on a single InAs/AlAs self-assembled quantum dot. A broad sideband at 1.2 meV of the zero phonon line is attributed to the exciton-acoustic phonon interaction via deformation potential coupling. The piezoelectric coupling of the exciton to long-wavelength phonons is also observed and gives rise to a narrow low-energy sideband at about 0.25 meV of the zero-phonon line. This band strengthens with decreasing density of photocreated free carriers, since they screen out the piezoelectric coupling mechanism. © 2009 American Institute of Physics.