Intraband polaron dynamics of excited carriers in InAs/In _xAl _1-xAs quantum dots

The lifetime of excited carriers in InAs/InAlAs-on-InP quantum dots is investigated using intraband photoconductive (PC) spectra. A method is presented, based on the analysis of temperature dependence and line shape of PC signals, by which the dynamic properties are derived. Detailed analysis of PC measurements is a powerful method of studying the recombination dynamics. Temperature and energy dependencies are governed by strong electron-phonon interaction. The drop in PC signal with temperature is attributed to increased polaron relaxation due to the increased LA phonon population. Recombination at large detuning from LO phonon energy, as opposed to phonon bottleneck, renders an asymmetric line shape. The peak PC signal is redshifted due to an increased lifetime with detuning.