Effict of Spatially Varying Potential on Photon-Assisted Tunneling in Quantum Dots

概要

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A formula for photon-assisted tunneling (PAT) in seunicondtmctor quantum dots is derived for acase of low transmission rates throvxgh tvrnneling barriers, by using the generalized perturbationrnethod developed by Keldysh. We describe a new process giving rise to a dc current even inthe absence of bias voltage in which the dot is excited uniformly by an ac signal including mi-crowaves, and both the occupied and the unoccupied quantized states participate in the electricalcondtrction. In addition, the dc cturrent flows through the left and the right barriers via differentlevels. An electron tunnels into the dot from the barrier in which the higher energy level pumpedby absorbing a spatialy trnif'orm ac signal has a higher transfer rate and another one occupiedin the lower level tunnels out through the lcarrier in which the lower energy level has a highertransfer rate. This is in marked contrast to a dc current without bias voltage, which has beenexplained in terms of the process making trse of a single qtuantized state in an asymmetricallyexcited quanttrm dot. In order to open a new channel, it is necessary to prepare a particularlevel configturation, which is realized, for instance, b3' spatially varying the potenial.
社団法人日本物理学会の論文
1997-01-15