Photoconductivity in self-organized InAs quantum dots

Photoconductivity in self-organized InAs/GaAs quantum dots is reported. It is found that the photoconductivity ratio between the InAs dots and GaAs matrix increases with increasing temperature. We point out that the photoconductivity of InAs dots can be attributed to the thermal activation of photocarriers into the GaAs matrix, where the conduction takes place. We also found that self-organized InAs dots exhibit the effect of persistent photoconductivity (PPC). The PPC effect is interpreted in terms of the spatial separation of photocreated electrons and holes. After photoexcitation, the hole remains in the dot, and the electron is thermally activated into the GaAs barrier. The return of the electron is prevented from the existence of band bending at the InAs dot and GaAs interface. (C) 1998 American Institute of Physics. [S0021-8979(98)00221-7].