Photocurrent studies of the carrier escape process from InAs self-assembled quantum dots

We present a temperature- and bias-dependent photocurrent study of the excitonic interband transitions of InAs self-assembled quantum dots (QD's). It was found that the carrier escape process from QD's is dominated by hole escape processes. The main path for this hole escape process was found to be thermal-assisted hole tunneling, from the dot level to the GaAs barrier via the wetting layer as an intermediate state. Energy-dependent carrier tunneling from the QD's to the barrier was observed at low temperatures. Energy shifts due to the size-selective tunneling effect and the quantum-confined Stark effect are discussed and compared with the carrier redistribution effect in photoluminescence measurements.