Anomalous photocurrent in self-assembled InAs∕GaAs quantum dots

Carrier dynamics in self-assembled InAs∕GaAs quantum dots (QDs) is studied by photoluminescence (PL) and its complementary photocurrent (PC) spectroscopy. We found that carrier capture from the GaAs barriers, radiative recombination in InAs quantum dots, and tunneling among vertical QDs are very sensitive to applied bias voltage. An unusual behavior, by which the PL intensity presents steplike bias voltage dependence, has been observed. It is also consistently manifested in bias voltage dependent PC signals. We attribute this anomalous behavior to the interplay between the coupling of lateral QDs and tunneling among vertical ones.