A scheme of resonant tunneling through the metastable state of semiconductor quantum dot is presented and implemented in the transport study of freestanding InAs quantum dots grown on GaAs(001) under illumination using conductive atomic force microscopy. The metastable state is achieved by capturing one photoexcited Fermi hole in the valence energy level of InAs quantum dot. Resonant tunneling through single quantum dot can be observed at room temperature due to the existence of metastable state. The amplitude of tunneling current depends on the barrier arrangement and the concentration of photoexcited holes around the quantum dot, but is found steady when the height of dot varies from 1.8 to 9.9 nm, which are in good agreement with the proposed model. The experiment demonstrates a solution of room temperature operated single electron device to amplify the photocurrent by the singularity of resonant tunneling in epitaxial quantum dot.
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