Single-electron transistors with wide operating temperature range

Recent modern fabrication technology allows us for the fabrication of nanometer-scaled devices, which is possible to observe single electronic or single electron tunneling phenomena (Averin & Likharev, 1991; Likharev, 1988; Likharev, 1999; Hanna et al., 1991; Tucker, 1992). On the other hand, MOSFET (metal-oxide-semiconductor field effect transistor) devices with channel length below 20 nanometer (nm) are no more properly operated because the downscaling of MOS devices causes a large statistical fluctuation of the threshold voltage. A possible approach to overcome this problem is to use the single electron devices for future VLSI (very large scale integrated circuit) (Takahashi et al., 1995; Saitoh et al., 2001). Nanometer scale single electron devices have the following features, i.e., low power consumption and small size. These are key features to realize ultra high density circuits. Single electron circuits with new architecture are also possible because the basic operation of single electron devices is quite different from that of conventional semiconductor devices. There are two major requirements for single electron tunneling phenomena (Coulomb blockade) to occur (Averin & Lhikarev, 1991; Likharev, 1988; Likharev, 1999). Firstly, thermal energy 倦喋劇 must be much smaller than elemental charging energy 結態 に系 ⁄ . This ensures that the transport of charges is in fact governed by the Coulomb charging energy. This condition can be fulfilled either by lowering the temperature or by decreasing the capacitance which means to reduce the island size. Usually, experiments are performed at temperatures of a few mK and for structures with island sizes of a few hundred nanometers. Second requirement is related to tunnel resistance which must exceed the quantum resistance (h ね結態 ⁄ ≈ は.の kΩ). This condition ensures that the wave functions of excess electrons between the barriers are basically localized. On the other word, in the case of lower tunnel resistance, excess charges extend over the barriers so that no single electron tunneling event can be possible. There are several types of circuits where the single electron tunneling phenomena are being explored, such as single electron box (Likharev, 1999), single electron transistor (SET) (Tucker, 1992; Takahashi et al., 1995; Saitoh et al., 2001; Wolf et al., 2010; Sun et al., 2011; Lee et al., 2009), single electron pump (Ono et al., 2003), single electron turnstile (Moraru et al., 2011) and single electron circuits with several junctions (1D and 2D arrays) (Nuryadi et al., 2003; Nuryadi et al., 2005). A double junction system is most important single electron circuit because of a basic component of SET. At small applied voltage, the system remains in the Coulomb blockade state, and no current flows through the double junctions. On the other hand, at higher applied

Single electron transistors are widely perceived as the next generation devices, and beyond Moore's law devices due to their promising aspects of low power consumption, high switching speed, compact size, and importantly the ability to shrink to atomic scale. The single electron devices operation is based on the quantum phenomenon called "tunneling". Though the basic structure and operating principle of these devices is quite simpler, their fabrication and real-time operation is equally difficult, as it requires multiple conditions of Coulomb blockade to be satisfied for incoherent transport. This chapter provides comprehensive information about the single electron devices, starting from their benefit over other devices in the same series, associated concepts, operating principle, and the notable advancements in experimental as well as theoretical research on these devices. This chapter is expected to work as an absolute guide for any researcher interested in single electron devices.

First-principles study of MoS2, phosphorene and graphene based single electron transistor for gas sensing applications

The present paper discusses the investigation of electronic properties of anthracene-based single electron transistor (SET) operating in coulomb blockade region using Density Functional Theory (DFT) based Atomistix toolkit-Virtual nanolab. The charging energies of anthracene molecule in isolated as well as electrostatic SET environments have been calculated for analyzing the stability of the molecule for different charge states. Study also includes the analysis of SET conductance dependence on source/drain and gate potentials in reference to the charge stability diagram. Our computed charging energies for anthracene in isolated environment are in good agreement with the experimental values and the proposed anthracene SET shows good switching properties in comparison to other acene series SETs.

At present, the studies on magnetocaloric properties are mainly based on polycrystalline materials, which is not enough to reveal and understand the origin of their magnetocaloric effect. In addition, finding new room temperature magnetocaloric materials is crucial to the development and application for room temperature magnetic refrigeration. Here, we report the magnetic transitions, magnetic anisotropy, and magnetocaloric properties of single-crystal Mn5Ge3 and Mn5Ge3/Mn3.5Fe1.5Ge3 heterostructures with six (100) surfaces and the [001] growth direction prepared using the Sn flux method. Mn5Ge3 (Mn3.5Fe1.5Ge3) undergoes a sharp paramagnetic-collinear ferromagnetic transition at 299 (332) K and weak collinear-noncollinear ferromagnetic transition at 65 (35) K. Owing to the distinct spin arrangements and magnetic moments of Mn5Ge3 and Mn3.5Fe1.5Ge3, the magnetic anisotropy of the single crystal is stronger than that of the heterostructure below 299 K. Moreover, a large anisotropic magnetocaloric effect, wide operating temperature range, and large refrigeration capacity near room temperature are obtained in these two materials, especially the magnetocaloric effect of the heterostructure presents a tablelike shape due to the adjacent paramagnetic-collinear ferromagnetic transitions of Mn5Ge3 and Mn3.5Fe1.5Ge3. Under 0-3 T, the maximum magnetic entropy change, operating temperature range, and refrigeration capacity of the single crystal (heterostructure) are 5.19 (2.96) J kg-1 K-1, 43 (57) K, and 223 (169) J kg-1 when H//c, respectively. These features make them candidates for room temperature magnetic refrigeration.

This chapter focuses on the approach of nanotechnology toward nanoelectronics, various nanoelectronic devices, and their emerging applications in the various fields of life. It confines the people discussion to solid-state quantum effect and single electron devices. Solid-state quantum effect devices can be divided as follows: quantum dots, resonant tunneling diodes, and single electron transistors. Quantum dots of large dimensions from semiconductor material are synthesized by the top-down approach. A quantum dot solar cell utilizes quantum dots as the absorbing photovoltaic material. This chapter explains the functions and applications of various solid-state devices, along with the evolution of nanoelectronic devices from the microelectronic devices and circuits. This worldwide enterprise of engineering nanoscale devices is still ongoing, and it will definitely transform our computing and technology infrastructure in the future.

Nano-island fabrication by electron beam lithography and selective oxidation of Al-rich AlGaAs layers for single electron device application

We show the control of a charging energy in chemically assembled nanoparticle single-electron transistors (SETs) by altering the core diameter of Au nanoparticles. The charging energy is a fundamental parameter that decides the operating temperature of SETs. Practical application of SETs requires us to regulate the value of the charging energy by tuning the diameter of quantum dots. In this study, we used 3.0, 5.0 and 6.2 nm diameter synthesized Au nanoparticles as a quantum dot in the SETs. The total capacitances and charging energy of the SETs were evaluated from the rhombic Coulomb diamonds attributed to a single Coulomb island. The capacitance and charging energy matched with a concentric sphere model much better than with a simple sphere model. The operating temperatures of the SETs suggested that a charging energy 2.2 times greater than the thermal energy was required for stable operation, in theory. These results will help us to select an appropriate core diameter for the Au nanoparticles in practical SETs.

An accurate battery model is essential for precise estimation of battery performance indicators, such as state of charge (SoC), state of health (SoH), etc. It helps in determining the optimum energy management and therefore, optimum utilization of the battery capacity. Some of the battery model parameters may change with the variation of environmental conditions, such as operating temperature, and therefore, accurate temperature compensated model estimation is necessary to minimize the error in battery model and SoC estimation. This article presents a novel parameters extraction method for the Thevenin equivalent circuit model of Li-ion batteries considering their resiliency on temperature effect. The proposed approach represents each of the RC parallel circuits of the Thevenin-based equivalent circuit battery model as a first-order linear time-invariant (LTI) system. The resistance and capacitance values for each of the RC circuits in the model have been identified as the parameters of a standard LTI system using the system identification theory and represented them as the temperature-compensated model parameters. The proposed model can be applied to various applications, such as SoC, SoH estimation, and battery energy management. In order to demonstrate the suitability of the proposed modeling approach, the model is augmented with the conventional extended Kalman filter to enable accurate SoC estimation under varying operating temperatures. The accuracy and effectiveness of the proposed modeling approach and its suitability to enhance SoC estimation under a wide operating temperature range (-5 to 45 °C) have been validated through laboratory experiments in the LabVIEW platform.

n+InAs(Si) epitaxial thin films heavily doped by silicon and Hall effect magnetic field sensors based on this structures have been fabricated and studied. We have demonstrated the successful formation of highly doped InAs thin films (∼100 nm) with the different intermediate layer arrangement and appropriate electron mobility values. Hall sensors performance parameters have been measured in wide temperature range. Obtained sensitivity varied from 1 to 40 Ω/T, while the best linearity and lower temperature coefficient have been found in the higher doped samples with lower electron mobility. We attribute this to the electron system degeneracy and decreased phonon contribution to electron mobility and resistance.

Radiation induced degradation of widely used bipolar voltage comparators was investigated in wide temperature range from high to liquid nitrogen temperatures. It was obtained, that the parametric degradation is significantly greater at low temperature measurements.

The mostly widely used lithium (Li) batteries, including lithium-ion (Li-ion) batteries, are activated via organic solvent based electrolytes that are highly flammable. The flammable electrolyte can potentially impose impediments to large-format battery device implementation because, under abuse conditions (e.g., internal short circuit, overcharge, crush, etc.), Li batteries can be hazardous due to heat generation which can potentially lead to toxic/flammable material release, fire and over-pressurization/explosion [1]. These hazards represent major concerns for power source platforms populated by personnel, sensitive equipment and/or vital structures. Recent high-profile incidents involving energy dense batteries (e.g., the Boeing 787 Dreamliner battery fire incident [2]) have increased public awareness of battery safety and resulted in intensified scrutiny for the processes used to develop, manufacture, certify and transport Li batteries. Here we present ADA efforts in the development of a Li battery technology comprised from a nonflammable, high performance, room temperature ionic liquid (RTIL)-based or hydrofluoroether (HFE)-based electrolytes and a nano-engineered, atomic layer deposition (ALD) functional material coated, high voltage, high energy density cathode (i.e., high voltage LiCoO2 or HV-LCO). We demonstrate that such combinations can afford a Li battery technology with an unprecedented high energy density (over state-of-the-art Li-ion or Li batteries), high rate capability, a wide operation temperature range, long cycle life at room temperature (RT) and temperature extremes and safety. Figure 1 shows electrolyte flammability test results. A lighter was used to ignite the electrolyte in a watch glass dish in open air. An organic solvent based, Li-ion battery baseline (conventional) electrolyte was ignited and self-burning when the ignitor was moved away. Each of the RTIL- and HFE-based electrolytes did not ignite and, no self-combustion was observed. Figure 2 shows discharge voltage profiles of Li/HV-LCO cells with RTIL- and HFE-based nonflammable electrolytes as a function of temperature. The cells were cycled between 3-4.6V. At RT, the cells delivered a high specific capacity/energy (> 200 mAh/g and > 800 Wh/kg, cathode active weight). At 50°C, the cells delivered a slightly higher (1-3%) specific capacity than RT. At -20°C, the cells were cycled at C/10 rate and delivered ~75% of the capacity at RT (~155 mAh/g). At -40°C, the cells were cycled at C/20 rate. The HFE-based electrolyte cell delivered a much higher specific capacity (66.5 mAh/g) than the RTIL-based (negligible). Figure 3 shows excellent rate capability of the RTIL-based electrolyte with 85% capacity retention at 10C rate. Figure 4(a) shows high voltage cycle life between 3-4.6V at RT for pristine LCO and HV-LCO based Li cells using the RTIL-based electrolyte. The pristine LCO cells experienced a rapid capacity fade while the HV-LCO cells demonstrated excellent cycle life stability with > 92% capacity retention after 100 cycles. We attribute the excellent HV-LCO high voltage cycle performance to the ALD functional material coating on LCO; this coating effectively suppresses the degradation root cause, i.e., the Co4+ dissolution and hexagonal to monoclinic phase transition [3]. We also evaluated cycle life at an extreme high temperature of 75°C. Figure 4(b) shows high voltage cycle life test data for pristine LCO and HV-LCO based lithium cells using RTIL-based electrolyte with additives. The cells were cycled between 3-4.5V. The pristine LCO based cell still faded much more quickly than the HV-LCO based cell; the latter exhibited an extraordinary high voltage high temperature cycle resiliency (97% capacity retention after 30 cycles, vs. 75% of the pristine LCO) even at the extreme high temperature of 75°C. We attribute the outstanding cycle stability at 75°C to the synergistic benefits of nano-engineered cathode and passivation protection from the electrolyte additives. Our study highlights the importance of combining high performance, safe electrolyte with nano-engineered cathode (e.g., ALD nano-engineered LCO) to render the resultant lithium battery with unprecedented energy density (gained from the high voltage operation), high rate capability, safety (nonflammability) and robust cycle life over a wide temperature range particularly at the extreme high temperatures (e.g., 75°C). We demonstrate that our Li battery technology is ideally suited for many high energy density and safety demanding applications, such as, electric drive vehicles, consumer electronics, medical, space and military applications. References Peter Roth and Christopher J. Orendorff, Electrochem. Soc. Interface, Summer 2012, page 44.“FAA Grounds Boeing 787 Dreamliner for Battery Problems”, Aviation International News, January 2013Akira Yano, Masahiro Shikano, Atsushi Ueda, Hikari Sakaebe, and Zempachi Ogumi, Electrochem. Soc., 164, A6116 (2017). Figure 1

Electrolyte is an important component in redox flow batteries (RFBs) that determines the current capability, potential window, and safety, but both aqueous and nonaqueous electrolytes have their intrinsic limits. Here, we develop the proof‐of‐concept hybrid electrolyte chemistry to enable the design of safe and wide‐temperature RFBs. In addition to the non‐flammable characteristics, the hybrid electrolyte also inherits the high electrochemical stability and wide operational temperature range. It can show a potential window of 2.5 V and maintain high ion conductivities at low temperatures. It also enables LiI to achieve high Coulombic efficiencies of >99.9 %, showing long cycling stability over 800 cycles. Moreover, it enables the successful operation of Zn/LiI RFBs at −20 °C for 150 cycles with nearly no capacity loss. This study highlights the great potential of hybrid electrolyte chemistry for the approach of safe and high‐performance large‐scale energy storage systems in wide temperature ranges.

Localized data conversions for sensors placed under harsh environmental conditions often require Analog to Digital Converters (ADC) capable of working under wide operating temperature range. Even though the fastest analog to digital converter, flash ADC is omitted from the high temperature regime due to the requirements of reference voltage source, reference voltage divider and a comparator array capable of providing stable operation under wide operating temperatures. A CMOS Schmitt inverter-based internal reference comparator array for flash ADC which is efficient in terms of area and power consumption, capable of working under wide temperature range is presented in this paper. The proposed idea replaces the reference voltage source, resistive reference voltage divider and differential comparator array of a conventional flash ADC by an array of suitably sized Schmitt inverters. The circuit was simulated for static and dynamic characteristics with gpdk 180 nm library using cadence virtuoso simulation suite. The voltage transfer characteristic curve (VTC) of the proposed comparator array was found invariable when a temperature sweep in the range of −40 to 170 degree Celsius was performed. Each of the comparator in the proposed array consumes a silicon area of 40.68 and the average dynamic power consumption per cycle is estimated as 103.1 uW.

The present paper discusses charge stability and conductance analyses of benzene- and zigzag graphene fragment-based single-electron transistors (SETs) operating in the Coulomb blockade regime. Graphene and benzene are modeled using density functional theory-based ab initio analyses, treating the interaction between graphene/benzene and the SET environment self-consistently. The devices consist of an oriented graphene/benzene island coupled with source and drain electrodes. The charging energy as a function of the external gate potential has been analyzed to verify the dependence of the charge stability and conductance of the oriented SETs on the source/drain bias and gate potential. Comparative analysis of these models shows that the SET with vertically oriented graphene is more stable and has better conductance in comparison with the benzene-based SET.