Candidate For Future Electronic Devices Research Articles

Electronic and spin transport in Bismuthene with magnetic impurities

Topological insulators have remained as candidates for future electronic devices since their first experimental realization in the past decade. The existence of topologically protected edge states could be exploited to generate a robust platform and develop quantum computers. In this work we explore the role of magnetic impurities in the transport properties of topological insulators, in particular, we study the effect on the zigzag bismuthene nanoribbon edge states conductivity. By means of realistic abinitio calculations we simulate the interaction between magnetic adatoms and topological insulators, furthermore, our main goal is to obtain the transport properties for large samples as it would be possible to localize edge states at large scales.

Mechanically Strong and Electrically Conductive Polyethylene Oxide/Few-Layer Graphene/Cellulose Nanofibrils Nanocomposite Films

In this work, a cellulose nanofibrils (CNFs)/few-layer graphene (FLG) hybrid is mechanically stripped from bamboo pulp and expanded graphene (EG) using a grinder. This strategy is scalable and environmentally friendly for high-efficiency exfoliation and dispersion of graphene in an aqueous medium. The in situ-generated CNFs play a key role in this process, acting as a "green" dispersant. Next, the obtained CNFs-FLG is used as a functional filler in a polyoxyethylene (PEO) matrix. When the composition of CNFs-FLG is 50 wt.%, the resultant PEO/CNFs-FLG nanocomposite film exhibits a Young's modulus of 1.8 GPa and a tensile strength of 25.7 MPa, showing 480% and 260% enhancement as compared to those of the pure PEO film, respectively. Remarkably, the incorporation of CNFs-FLG also provides the nanocomposite films with a stunning electrical conductivity (72.6 S/m). These attractive features make PEO/CNFs-FLG nanocomposite films a promising candidate for future electronic devices.

Electronic properties of pure and doped NbS2 and WS2 monolayers

The two dimensional (2D) layered materials have attracted significant research interest from few decades. The layered transition metal dichalcogenides (TMDCs) are also a family member of 2D materials with formula of the type MX2, where M is a transition metal (Mo and W) and X is a chalcogen atom (S and Se). MoS2 and WS2 are being studied among other layered TMDCs. From application point of view, it is necessary to understand the electronic properties of these materials for their potential candidature in the electronic devices. Therefore, a comparative systematic study is presented to understand the electronic properties of pure and doped NbS2 and WS2 monolayer by using the density functional theory (DFT). The electronic properties of WS2 can be tuned by the external perturbations such as doping among others. Here, the change in the electronic properties, like band structure and density of states (DOS), due to the doping effect are being discussed. These properties are further elaborated to understand the effect of doping concentration. The reported results are in good agreement with the experimental observations. These findings suggest that WS2 monolayer may be the potential candidate for future electronic devices like memristors, resistive memory devices, atomic switches, optoelectronic and neuromorphic computing applications.

Quasi-Zero Dimensional Halide Perovskite Derivates: Synthesis, Status, and Opportunity

In recent decades, many technological advances have been enabled by nanoscale phenomena, giving rise to the field of nanotechnology. In particular, unique optical and electronic phenomena occur on length scales less than 10 nanometres, which enable novel applications. Halide perovskites have been the focus of intense research on their optoelectronic properties and have demonstrated impressive performance in photovoltaic devices and later in other optoelectronic technologies, such as lasers and light-emitting diodes. The most studied crystalline form is the three-dimensional one, but, recently, the exploration of the low-dimensional derivatives has enabled new sub-classes of halide perovskite materials to emerge with distinct properties. In these materials, low-dimensional metal halide structures responsible for the electronic properties are separated and partially insulated from one another by the (typically organic) cations. Confinement occurs on a crystal lattice level, enabling bulk or thin-film materials that retain a degree of low-dimensional character. In particular, quasi-zero dimensional perovskite derivatives are proving to have distinct electronic, absorption, and photoluminescence properties. They are being explored for various technologies beyond photovoltaics (e.g. thermoelectrics, lasing, photodetectors, memristors, capacitors, LEDs). This review brings together the recent literature on these zero-dimensional materials in an interdisciplinary way that can spur applications for these compounds. The synthesis methods, the electrical, optical, and chemical properties, the advances in applications, and the challenges that need to be overcome as candidates for future electronic devices have been covered.

Formation of Coherent 1H-1T Heterostructures in Single-Layer MoS2 on Au(111).

Heterojunctions of semiconductors and metals are the fundamental building blocks of modern electronics. Coherent heterostructures between dissimilar materials can be achieved by composition, doping, or heteroepitaxy of chemically different elements. Here, we report the formation of coherent single-layer 1H-1T MoS2 heterostructures by mechanical exfoliation on Au(111), which are chemically homogeneous with matched lattices but show electronically distinct semiconducting (1H phase) and metallic (1T phase) character, with the formation of these heterojunctions attributed to a combination of lattice strain and charge transfer. The exfoliation approach employed is free of tape residues usually found in many exfoliation methods and yields single-layer MoS2 with millimeter (mm) size on the Au surface. Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), scanning tunneling microscopy (STM), and scanning tunneling spectroscopy (STS) have collectively been employed to elucidate the structural and electronic properties of MoS2 monolayers on Au substrates. Bubbles in the MoS2 formed by the trapping of ambient adsorbates beneath the single layer during deposition, have also been observed and characterized. Our work here provides a basis to produce two-dimensional heterostructures which represent potential candidates for future electronic devices.

Homogeneous 2D MoTe2 CMOS Inverters and p-n Junctions Formed by Laser-Irradiation-Induced p-Type Doping.

Among all typical transition-metal dichalcogenides (TMDs), the bandgap of α-MoTe2 is smallest and is close to that of conventional 3D Si. The properties of α-MoTe2 make it a favorable candidate for future electronic devices. Even though there are a few reports regarding fabrication of complementary metal-oxide-semiconductor (CMOS) inverters or p-n junction by controlling the charge-carrier polarity of TMDs, the fabrication process is complicated. Here, a straightforward selective doping technique is demonstrated to fabricate a 2D p-n junction diode and CMOS inverter on a single α-MoTe2 nanoflake. The n-doped channel of a single α-MoTe2 nanoflake is selectively converted to a p-doped region via laser-irradiation-induced MoOx doping. The homogeneous 2D MoTe2 CMOS inverter has a high DC voltage gain of 28, desirable noise margin (NMH = 0.52 VDD , NML = 0.40 VDD ), and an AC gain of 4 at 10 kHz. The results show that the doping technique by laser scan can be potentially used for future larger-scale MoTe2 CMOS circuits.

A Universal Length-Dependent Vibrational Mode in Graphene Nanoribbons

Graphene nanoribbons (GNRs) have attracted considerable interest, as their atomically tunable structure makes them promising candidates for future electronic devices. However, obtaining detailed information about the length of GNRs has been challenging and typically relies on low-temperature scanning tunneling microscopy. Such methods are ill-suited for practical device application and characterization. In contrast, Raman spectroscopy is a sensitive method for the characterization of GNRs, in particular for investigating their width and structure. Here, we report on a length-dependent, Raman-active low-energy vibrational mode that is present in atomically precise, bottom-up-synthesized armchair graphene nanoribbons (AGNRs). Our Raman study demonstrates that this mode is present in all families of AGNRs and provides information on their length. Our spectroscopic findings are corroborated by scanning tunneling microscopy images and supported by first-principles calculations that allow us to attribute this mode to a longitudinal acoustic phonon. Finally, we show that this mode is a sensitive probe for the overall structural integrity of the ribbons and their interaction with technologically relevant substrates.

Graphene Membranes for Hall Sensors and Microphones Integrated with CMOS-Compatible Processes

Graphene is a promising candidate for future electronic devices because of its outstanding electronic and mechanical properties. The high charge carrier mobility in graphene, particularly in substr...

Fowler-Nordheim tunneling characteristics of graphene/hBN/metal heterojunctions

The heterostructures of low-dimensional materials are considered promising candidates for future electronic devices. In this work, we manifest the interlayer hexagonal boron nitride (hBN) thickness dependent tunneling characteristics of graphene/hBN/metal heterojunction back-gated field effect transistors (FETs). Direct tunneling of charge carriers through the ultrathin hBN layer is noticed at low bias voltages. Besides, Fowler-Nordheim tunneling takes place at high bias voltages revealing an increase in the barrier height with an interlayer film thickness. In addition, the back-gate dependent tunneling properties of graphene/hBN/metal heterojunction back-gated FETs are investigated. Furthermore, the Fermi level of graphene is tuned via back-gate voltages that results in the modification of the tunneling current, threshold voltage, and barrier height of the device. This could be an effective approach to modify the tunneling features of vertical heterostructures for their prospective role in next generation high performance electronic devices.

High‐Performance n‐ and p‐Type Field‐Effect Transistors Based on Hybridly Surface‐Passivated Colloidal PbS Nanosheets

AbstractColloidally synthesized nanomaterials are among the promising candidates for future electronic devices due to their simplicity and the inexpensiveness of their production. Specifically, colloidal nanosheets are of great interest since they are conveniently producible through the colloidal approach while having the advantages of two‐dimensionality. In order to employ these materials, according transistor behavior should be adjustable and of high performance. It is shown that the transistor performance of colloidal lead sulfide nanosheets is tunable by altering the surface passivation, the contact metal, or by exposing them to air. It is found that adding halide ions to the synthesis leads to an improvement of the conductivity, the field‐effect mobility, and the on/off ratio of these transistors by passivating their surface defects. Superior n‐type behavior with a field‐effect mobility of 248 cm2 V−1 s−1 and an on/off ratio of 4 × 106 is achieved. The conductivity of these stripes can be changed from n‐type to p‐type by altering the contact metal and by adding oxygen to the working environment. As a possible solution for the post‐Moore era, realizing new high‐quality semiconductors such as colloidal materials is crucial. In this respect, the results can provide new insights which helps to accelerate their optimization for potential applications.

Variability in Output Characteristics of Single-Walled Carbon Nanotube Thin-Film Transistors

Single-walled carbon nanotube (CNT) based thin-film transistors (TFTs) are promising candidates for future electronic devices because of their excellent properties. However, device-to-device performance variability of TFTs can pose challenging problems, which is rooted in the randomness of CNT networks, the variation in individual CNT properties due to change in chirality, and the fabrication imperfections. This paper presents a systematic study of variability in I-V characteristics through a combination of experimental and theoretical analysis of the major sources that cause performance variation. The sources of variation including the percentage of metallic CNTs (m-CNTs), threshold voltage, CNT mean length, and CNT network density have been studied separately. The analysis shows that the presence of m-CNTs is a major source contributing to the performance variation for short channel TFTs, but its effect reduces for large channel length transistors. The threshold voltage is found to be the major source of variation for long channel TFTs. A better consistency in performance can be guaranteed for TFTs with larger channel area, which ensures a smaller variation in CNT network density and CNT mean length. These results provide key insights into the variability estimation of I-V characteristics of CNT-based devices, which is vital for reliability studies of CNT-TFTs based circuits for different electronic applications.

Multiferroic Hysteresis Loop.

Multiferroics, showing both ferroelectric and magnetic order, are promising candidates for future electronic devices. Especially, the fundamental understanding of ferroelectric switching is of key relevance for further improvements, which however is rarely reported in literature. On a prime example for a spin-driven multiferroic, LiCuVO4, we present an extensive study of the ferroelectric order and the switching behavior as functions of external electric and magnetic fields. From frequency-dependent polarization switching and using the Ishibashi-Orihara theory, we deduce the existence of ferroelectric domains and domain-walls. These have to be related to counterclockwise and clockwise spin-spirals leading to the formation of multiferroic domains. A novel measurement—multiferroic hysteresis loop—is established to analyze the electrical polarization simultaneously as a function of electrical and magnetic fields. This technique allows characterizing the complex coupling between ferroelectric and magnetic order in multiferroic LiCuVO4.

Ab initioprediction of a new allotrope of two-dimensional silicon

Silicene, a promising candidate for future electronic devices, has been fabricated only on supporting substrates as silicon atom prefers to form the sp3 hybridization structure. Therefore, it's important to search more stable two-dimensional (2D) silicon allotropes and several 2D silicon allotropes have been proposed recently. In this work, we predict a new type of 2D silicon allotrope (called OTDS) based on ab initio structure, phonon-mode and molecular dynamics calculations. OTDS has the in-plane octagonal tiling (OT) pattern with dumbbell-like structures and silicon atoms in OTDS are four- and three-coordinated. OTDS is a semiconductor with a large band gap (about 1.5 eV by HSE calculation) and the band gap can be tuned effectively by the in-plane strain. Perspective and side views of the atomic structure of OTDS.

Electronic and optical properties of bilayer blue phosphorus

We investigate the electronic and optical properties of monolayer and stacking dependent bilayer blue phosphorus in the framework of density functional theory (DFT) and tight-binding approximations. We extract the hopping parameters of TB Hamiltonian for monolayer and bilayer blue phosphorus by using the DFT results. The variation of energy band gap with applied external electric field for two different stacks of bilayer blue phosphorus are also shown. We examine the linear response of the systems due to the external electromagnetic radiation in terms of the dielectric functions in the DFT theory. The relatively large electronic band gap and possibility of exfoliation form bulk structure due to weak interlayer coupling, make blue phosphorus an appropriate candidate for future electronic devices.

Atomistic study on dithiolated oligo-phenylenevinylene gated device

Thanks to their semiconducting behavior, conjugated molecules are considered as an attractive candidate for future electronic devices. Understanding the charge transport characteristics through such molecules for different device applications would accelerate the progress in the field of molecular electronics. In addition, it would become more feasible to introduce/enhance specific properties of molecular devices. This theoretical paper focuses on atomistic simulation and characterization of novel molecular FET employing dithiolated oligo-phenylenevinylene molecules. The simulation is validated by its agreement with the experimental measurements conducted on the same molecules. The employed molecule has oxygen linkers, which are responsible for the strongly nonlinear current characteristics on the molecular device. We perform a thorough atomistic device analysis to illustrate the principles behind the nonlinear current characteristics and the gating effect.

A Novel Carbon Nanotube Field Effect Transistor based Arithmetic Computing Circuit for Low-power Analog Signal Processing Application

Abstract There is a need to explore circuit application in new emerging technologies for their rapid commercialization as the CMOS technology is approaching its limits. Carbon Nanotube Field-Effect Transistor (CNFET) is a promising candidate for future electronic devices for low-power low-voltage digital or analog circuit application. In this paper, we presented a low-power, low- voltage CNFET operational amplifier (OPAMP) based analog arithmetic computing circuit such as inverting amplifier, non- inverting amplifier, summer, substractor, differentiator, and integrator for low-power analog signal processing application. The proposed computing circuits operation are studied by using HSPICE software for circuit simulation at 0.9 V input supply voltage. Simulation results show that the proposed computing circuits well suited for low-power low-voltage analog signal processing application for their lower power consumption, and high speed operation.

Simple Fabrication Technique for Field-Effect Transistor Array Using As-Grown Single-Walled Carbon Nanotubes

A carbon nanotube field-effect transistor (CNT-FET) is a promising candidate for future electronic devices; however, its fabrication process is still challenging. We propose a simple fabrication technique for CNT-FET arrays using as-grown single-walled CNTs (SWNTs) as the gate channel. In this study, a hydrophobic self-assembled monolayer (SAM) was used to restrict the catalyst-supporting area after the fabrication of an electrode array. Since it is known that droplets are trapped at rough edges of a hydrophobic surface, the deposition of a liquid-based catalyst, followed by alcohol catalytic chemical vapor deposition (ACCVD) produced SWNTs that grew only at the corners of electrode edges. The current–voltage (I–V) characterization of FETs with a 40 µm channel width showed that 98% of the fabricated devices were electrically connected and more than 50% were functional FETs (ION/IOFF > 102).

Microstructure of electroplated Cu(Ag) alloy thin films

Electroplated Cu(Ag) alloy thin films are potential candidates for future electronic devices in terms of lifetime and reliability compared to copper as the state of the art interconnect material. In the present paper we focus on the microstructure of Cu(Ag) alloy films considering the grain evolution as well as silver incorporation and segregation. We show that Ag alloying addition prevents room temperature recrystallization. Thermally induced grain growth occurs mainly between 180°C and 330°C. Silver can be incorporated as solid solution into the Cu matrix by up to 0.8at.% after annealing and even in higher concentrations in the as-deposited state, which is significantly above the equilibrium solubility limit. Precipitations are formed by the continuous mode and can be mainly found at the film surface but also inside the Cu(Ag) grains as ball-shaped particles. Based on our results a reliability improvement is expected by mechanical strengthening due to alloying effects while maintaining a low electrical resistivity and a {111} fiber texture.

Generation of size-selected gold nanoparticles by spark discharge — for growth of epitaxial nanowires

One-dimensional semiconductor nanowires are a promising candidate for future electronic devices. The epitaxial growth of nanowires is often mediated by metal seed particles, usually gold particles. In this paper the setup of a simple and robust technique to generate nanometer-sized aerosol gold particles by spark discharge is described. Furthermore we demonstrate for the first time that particles generated by spark discharge can be used to design advanced nanoelectronic structures, namely nanowires. In order to obtain compact, spherical particles suitable for nanowire growth, the sparkgenerated agglomerate particles were reshaped in a special compaction furnace. The reshaped particles were used to seed the growth of epitaxial GaP and InP nanowires, by metal organic vapor phase epitaxy, which was shown to be a reliable and reproducible method. This work indicates the possibility of using spark-discharge generated gold particles for the creation of new electronic devices even at large scale processing.

Genetic algorithm approach to aromatic molecules for nanoscale device

Over the next 10 years, the 40-year miniaturization revolution in silicon-based microelectronics will approach its ultimate nanometer-scale limits. Molecular electronics is a potential candidate for future electronic devices. However, it is currently very difficult to predict which molecules would be suitable for fabricating such devices because the number of organic molecules that are available is enormous. In this paper, we propose that a Genetic Algorithm (GA) could be used to survey molecules to determine those which would be appropriate for practical molecular devices. The molecules that were identified in this study have a long rigid shape and a small HOMO-LUMO gap.