Temperature-induced carrier escape processes studied in absorption of individual InxGa1-xAs quantum dots

Absorption spectra of individual InGaAs quantum dots located within a diode structure are measured over a wide temperature range (Tless than or equal to100 K) using photocurrent techniques. Strong saturation of the absorption with increasing excitation laser power is observed at low temperature whereas a nearly linear power dependence is measured at T=80 K in a wide range of incident powers. The observed suppression of the saturation is a result of the pronounced broadening of the absorption peak due to a faster hole escape from the ground state at elevated temperature. In addition, the consequent fast tunneling of the hole from the excited state is shown to lead to a further strong increase of the saturation power. The observation indicates that the electrical read out of the quantum dot population can be performed on a considerably faster time scale as the temperature is increased.