テラヘルツ電磁波を用いた量子ドット中のサブレベル間遷移の観測

We have investigated intersublevel transitions in single self-assembled InAs quantum dots (QDs) by using a single electron transistor geometry that consists of a QD and nanogap metal electrodes as a terahertz detector. Photocurrent distribution with respect to the Coulomb diamonds indicates that there are two mechanisms for the photocurrent generation. When the p shell was fully occupied, we observed rather simple photocurrent spectra induced by the p->d transitions. However, when the p shell was half-filled, the photocurrent spectra exhibited a complicated behavior, which we attribute to the fluctuation in electron configuration when the empty p state is filled back from the electrodes.

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