Polaron relaxation dynamics in InAs/GaAs self-assembled quantum dots

Polaron decay in n-type InAs quantum dots has been investigated using energy dependent, mid-infrared pump–probe spectroscopy. By studying samples with differing ground state to first excited state energy separations the relaxation time has been measured between ∼40 and View the MathML source. The low-temperature decay time increases with increasing detuning between the pump energy and the optical phonon energy and is maximum View the MathML source at View the MathML source. From the experimentally determined decay times we are able to extract a low-temperature optical phonon lifetime of View the MathML source for InAs QDs. We find that the polaron decay time decreases by a factor of ∼2 at room temperature due to the reduction of the optical phonon lifetime.