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Current–voltage characteristics of a quantum dot in double-barrier configuration, as formed in the nanoscale channel of silicon transistors, were analyzed both experimentally and theoretically. Single electron transistors (SET) made in a SOI-FET configuration using silicon quantum dot as well as phosphorus donor quantum dots were experimentally investigated. These devices exhibited a quantum Coulomb blockade phenomenon along with a detectable effect of variable tunnel barriers. To replicate the experimental results, we developed a generalized formalism for the tunnel-barrier dependent quantum Coulomb blockade by modifying the rate-equation approach. We qualitatively replicate the experimental results with numerical calculation using this formalism for two and three energy levels participated in the tunneling transport. The new formalism supports the features of most of the small-scaled SET devices.

A fluorobenzene based single electron transistor (SET) has been investigated for the detection of toxic gases viz. NH 3 , HCN, AsH 3 , and COCl 2 , within the framework of density functional theory (DFT) formalism based first-principles approach. Initially, the adsorption mechanism between the fluorobenzene quantum dot and the toxic gases (NH 3 , HCN, AsH 3 , and COCl 2 ) has been analyzed in terms of adsorption energy, distance of adsorption, DOS profiles and the charge transfer analysis. Later, the exclusive property of charge stability diagram of SET has been utilized to provide the necessary electronic fingerprints for detection of toxic gases. The results suggest that the fluorobenzene SET can be a potential sensor for proposed toxic gases based on the wide operational temperature range and high detection ability as witnessed from the electronic fingerprints.

We propose a method to study the thermodynamic behaviour of small systems beyond the weak coupling and Markovian approximation, which is different in spirit from conventional approaches. The idea is to redefine the system and environment such that the effective, redefined system is again coupled weakly to Markovian residual baths and thus, allows to derive a consistent thermodynamic framework for this new system-environment partition. To achieve this goal we make use of the reaction coordinate (RC) mapping, which is a general method in the sense that it can be applied to an arbitrary (quantum or classical and even time-dependent) system coupled linearly to an arbitrary number of harmonic oscillator reservoirs. The core of the method relies on an appropriate identification of a part of the environment (the RC), which is subsequently included as a part of the system. We demonstrate the power of this concept by showing that non-Markovian effects can significantly enhance the steady state efficiency of a three-level-maser heat engine, even in the regime of weak system-bath coupling. Furthermore, we show for a single electron transistor coupled to vibrations that our method allows one to justify master equations derived in a polaron transformed reference frame.

The electrostatic behavior of a hydrogen sulfide (H2S)-based double-gate (DG) single-electron transistor (SET) for the charge detection of toxic H2S gas has been investigated and its potential for switching applications with different orientations of H2S quantum dot explored. The electronic properties of the SET operating in the coulomb blockage region have been analyzed using advanced modeling techniques like density functional theory (DFT) and non-equilibrium Green’s function formalism, implemented in the QuantumWise-ATK. Through simulations, the charging energies of H2S molecules within the SET environment have been calculated, and the plot of total energy with gate voltage developed, which serves as a basis to generate the charge stability diagram. This diagram illustrates the nature of electron conduction in different charge states, which act as unique electronic fingerprints for the identification of H2S gas in different orientations. Moreover, it is observed that operating this SET model under negative gate bias is more energetically efficient than under positive bias.

Surface acoustic waves (SAWs) have been utilized as a platform for single-electron transistors. When superposed with the split-gate potential, propagating SAWs create moving potential wells. We demonstrate the total potential landscape using the Laplace equation and apply the one-dimensional time-independent Schrödinger equation to determine the conditions necessary for single-electron transport. Our findings reveal that the ratio between the SAW amplitude and the split-gate voltage varies with the SAW wavelength and the absolute value of the gate voltage. We propose essential conditions for single-electron transport based on the ratios derived from our calculations, which can be applied to other material systems.

The dependence of the entropy and heat capacity on applied drain and source bias and temperature in a few-nanometre-scale dopant atom quantum dot (QD) single-electron transistor (SET) has been investigated theoretically. In this system, the quantisation energy is comparable to the Coulomb charging energy. To make this study relevant, we choose energy scales matching experimental work on dopant atom QD SETs capable of room-temperature operation. The entropy of both a single QD, and double QDs, is investigated, where the latter provides additional information for a simple multiple QD system. Energy state diagrams are used to explain resonant tunnelling features in the Coulomb diamond plot and the Gibbs entropy S. For well-defined states within Coulomb diamonds, if spin is neglected, S → 0 at low temperature. In contrast, at finite drain bias, electron transport via higher energy quantised states increases their occupation probability, significantly perturbing S. Within regions of constant average current, the entropy reaches a maximum Smax=kBln⁡M, for M ‘effective’ states. The single-electron heat capacity is extracted, using S vs. temperature plots. A Schottky anomalous heat capacity-like peak occurs, linking single-particle dynamics to macroscopic, many-particle behaviour.

Unprecedented growth in CMOS technology and demand of high-density integrated circuits (ICs) in semiconductor industry has motivated to research community towards the development of MOS technology from micrometre regime to nano-meter regime. This paper presents the development of MOS technology from classical MOS technology to non-classical MOS technology and their extensions of learning towards the machine. Firstly, the studies are analysed with the scaling and limitations of bulk MOSFET beyond 100 nm in terms of constant and voltage field scaling and various short channel effects. Then we investigated the non-classical device architecture beyond 32 nm such as multiple-gate field-effect transistors, SOI MOSFETS, FINFETs, and gate-all-around FETs for the replacement of traditional CMOS devices. Next, we discussed the different architectures in the sub nano-technology regime. These structures include Carbon Nano Transistors, Single Electron Transistors (SET), Graphene Nano Ribbon, Nano Wire, and Nano Sheet Transistors. It is very conceivable that these kinds of devices will be utilized in the construction of high-density integrated electronic computers in near future. Lastly, we extend our studies on different machine learning method like ANN, KNN, DNN and Random Forest for the optimization of MOSFET, SOI FET, TFET, FinFET and GAA FET.

We report on low-temperature noise measurements of a single electron transistor (SET) immersed in superfluid 4 He. The device acts as a charge sensitive electrometer able to detect the fluctuations of charged defects in close proximity to the SET. In particular, we measure telegraph switching of the electric current through the device originating from a strongly coupled individual two-level fluctuator. By embedding the device in a superfluid helium immersion cell, we are able to systematically control the thermalizing environment surrounding the SET and investigate the effect of the superfluid on the SET noise performance. We find that the presence of superfluid 4 He can strongly suppress the switching rate of the defect by cooling the surrounding phonon bath.

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.

A density functional theory (DFT)–based first principle approach has been employed to investigate the suitability of chlorobenzene-based single-electron transistor (SET) for the detection of few toxic gases such as hydrogen cyanide, arsine, and phosgene. The adsorption aspect of toxic gas molecules on the chlorobenzene with different orientations has been analyzed. The attributes such as charge density, molecular energy spectrum, density of states, and Mulliken population have been computed to scrutinize the effect of gas molecules on the surface of chlorobenzene. The sensing mechanism of adsorbate (toxic gases) with the adsorbent (chlorobenzene) has been authenticated in a single-electron transistor (SET) environment through total energy vs. gate voltage plot and charge stability diagram. The recovery time of the chlorobenzene-based SET gas sensor on the adsorption of HCN, AsH 3 , and COCl 2 has been computed as 1.93 ns, 0.45 ns, and 36.31 ns, respectively. Based on these findings, it is interesting to see that the COCl 2 gas molecule shows strong physical adsorption with the most significant adsorption distance (3.629 Å) with chlorobenzene, while AsH 3 -adsorbed chlorobenzene SET displays a low recovery time in comparison with other considered gases. The present analysis confirms a significantly better range of detection and improved recovery time using chlorobenzene-based single-electron transistor. Graphical abstract