Giant mesoscopic photoconductance fluctuations in Ge/Si quantum dot system

Abstract

We studied the impact of weak photon flux on the electron transport in strongly localized quantum dot system. Exploring devices with narrow transport channels lead to the observation of giant fluctuations of the photoconductance, which is attributed to the strong dependence of hopping current on the filling of dots by holes. This phenomenon has the potential to detect a single photoexcited carrier for a wide range of wavelength. In our experiments, single-photon mode operation is indicated by the linear dependence of the frequency of photoinduced fluctuations on the light intensity and the steplike response of conductance on the pulse excitation. © 2011 American Institute of Physics.