Analytical Modeling of Current and Quantum Capacitance of Single-Electron Transistor with Island Made of Armchair WSe 2
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https://doi.org/10.1007/s11664-020-08511-1 Ó 2020 The Minerals, Metals & Materials Society
Analytical Modeling of Current and Quantum Capacitance of Single-Electron Transistor with Island Made of Armchair WSe2 Nanoribbon M.K. BERA
1,2
1.—Department of Physics, Maharishi Markandeshwar (Deemed to be University), Mullana, Ambala, Haryana 133207, India. 2.—e-mail: [email protected]
Single-electron transistors (SETs), which operate by quantum-mechanically controlled coulomb blockade and the single-electron tunneling effect, are promising candidate future nanoelectronic devices. A physics-based analytical model is developed to study the current and quantum capacitance of a SET with an island made of monolayer tungsten diselenide (WSe2) nanoribbon in an armchair pattern. It is noteworthy that the SET current is not degraded much in the coulomb blockade region, whereas outside this region, the SET current decreases with varying width of the nanoribbon, presumably due to the greater width of the potential well in the island that lowers the tunneling rate. Since atomically thin nanoribbon possesses quantum capacitance, which might cause further degradation in the SET performance, its influences are also studied. A three-band nearest-neighbor tight-binding model is applied to assimilate the details and information of the energy band formation into the quantum capacitance estimation. Key words: Single-electron transistor, WSe2 nanoribbon, quantum capacitance, TMDC
INTRODUCTION Single-electron transistors (SETs) are promising nanodevices that exhibit a unique type of switching characteristic based on the principle of quantummechanical coulomb blockade and the single-electron tunneling effect.1–5 This allows the miniaturization of circuits while offering the benefits of reduced power consumption and high operating speed. A SET can transfer electrons one by one. The transfer of electrons is directed by the coulomb interaction and occurs on a minute conductive layer called an island6–9 that is analogous to the channel of a metal–oxide–semiconductor field-effect transistor (MOSFET). Although the theoretical idea of the SET was first proposed by Averin and Likharev in 1985, the first
(Received June 1, 2020; accepted September 22, 2020)
SET (made entirely out of metals) was demonstrated experimentally in 1987 by Fulton and Dolan.10 Unfortunately, it only worked at extremely low temperatures (1.1 K to 4.2 K), raising concerns about its functionality at room temperature for practical implementation.11 However, operation of SETs at room temperature was successfully demonstrated thereafter using a silicon island.12 The use of Si as an island confirms the influence of the island material on the SET operation, playing a key role in solving the limitations of SETs. Therefore, SETs made of new island materials such as two-dimensional (2D) graphene have been demonstrated recently.13,14 However, the electrical properties of island materials, for instance the carrier mobility and electron transport, govern the operation of the SE
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