Control of single-electron-tunneling characteristics in Si multidot structure for applying to nanodot automaton

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For the application to nanodot automaton and ultimately-low-consumption single-electron memory, we fabricated two-dimensional (2D) Si-multidot-channel field-effect transistors (FETs) and investigated their single-electron/hole-tunneling (SET/SHT) characteristics. In addition, we also simulated the alternative current characteristics of 2D random-multidot FETs for the realization of one-by-one transfer of electrons. The main results from this project are listed below.(1)The fabricated 2D Si-multidot-channel FETs show current oscillation due to the Coulomb blockade (CB) phenomenon below 70K, indicating the realization of SET/SHT. From the SET/SHT characteristics, we concluded that a carrier percolation path between source and drain electrodes, considering a string of dots, namely, a series of tunnel junctions, is formed in the 2D multidot channel, and that the highest-resistance tunnel junctions dominate the carrier transport. Moreover, by illuminating light and by applying side-gate bia … More s, the generation and/or shift of the current peaks were observed. These phenomena can be explained by the model in which the light illumination and side-gate bias supply an additional charge to a dot adjacent to the current percolation path.(2)The current fluctuation in SHT characteristics of the 2D Si-multidot-channel FET was observed in the particular ranges of drain voltage and gate voltage. This phenomenon is attributed to the time-dependent charging-discharging and polarity-switching of the dots adjacent to the current percolation path.(3)By Kelvin-probe force microscopy, we observed directly the carrier flowing in the Si multidot channel during the transistor operation. At room temperature, we successfully imaged the carrier flowing in a part of the channel, for the first time.(4)We investigated numerically the alternating-current characteristics in 2D random-multidot-channel FETs using the CB orthodox theory. It was found that the turnstile operation and single-electron pump operation meaning that electrons are transferred one by one can be performed. These operations can be interpreted using the stability diagram of the multidot FET. Less