We explore nanoribbons from topological two-dimensional stanene as channel material in tunnel field effect transistors. This novel technological option offers the possibility to build pure one-dimensional (1D) channel devices (comprised of a 1D chain of atoms) due to localized states in correspondence of the nanoribbon edges. The investigation is based on first-principle calculations and multi-scale transport simulations to assess devices performance against industry requirements and their robustness with respect to technological issues like line edge roughness, detrimental for nanoribbons. We will show that edges states are robust with respect to the presence of non-idealities (e.g., atoms vacancies at the edges), and that 1D-channel TFETs exhibit interesting potential for digital applications and room for optimization in order to improve the Ion/Ioff at the levels required by the ITRS, while opening a path for the exploration of new device concepts at the ultimate scaling limits.
A tunneling field effect transistor based on armchair graphene nanoribbons is studied using ballistic quantum transport simulation based on 3D real space nonequilibrium Green's function formalism. By introducing a pocket doping region near the source, the performance of GNRs TFET is improved in terms of larger on current and steeper subthreshold swings compared to conventional tunneling FET. It is also found that pocket region introduces two interesting features. By increasing the pocket length the ambipolar can be effectively suppressed. Furthermore, there is negative trans-conductance at neg…
A heterojunction tunneling field effect transistor based on armchair graphene nanoribbons is proposed and studied using ballistic quantum transport simulation based on 3D real space nonequilibrium Green's function formalism. By using low band gap nanoribbons as the source/drain material, the hetero- structure shows better performance including higher on current, lower off current, and improved steep subthreshold swings compared with homostructure. It is also found the device performance greatly depends on the source/drain dopping density. High doping density leads to fewer density states in th…
We present an atomistic 3D simulation study of the performance of graphene nanoribbon (GNR) Schottky barrier (SB) FETs and transistors with doped reservoirs (MOSFETs) by means of the self-consistent solution of the Poisson and Schrodinger equations within the non-equilibrium Green's function (NEGF) formalism. Ideal MOSFETs show slightly better electrical performance, for both digital and THz applications. The impact of non-idealities on device performance has been investigated, taking into account the presence of single vacancy, edge roughness and ionized impurities along the channel. In gener…
We propose an analytical device model for a graphene nanoribbon field-effect transistor (GNR-FET). The GNR-FET under consideration is based on a heterostructure which consists of an array of nanoribbons clad between the highly conducting substrate (the back gate) and the top gate controlling the dc and ac source-drain currents. Using the model developed, we derive explicit analytical formulas for the GNR-FET transconductance as a function of the signal frequency, collision frequency of electrons, and the top gate length. The transition from the ballistic and to strongly collisional electron tr…
We present an analytical device model for a field-effect transistor based on a heterostructure which consists of an array of nanoribbons clad between the highly conducting substrate (the back gate) and the top gate controlling the source-drain current. The equations of the model of a graphene nanoribbon field-effect transistor (GNR-FET) include the Poisson equation in the weak nonlocality approximation. Using this model, we find explicit analytical formulas for the spatial distributions of the electric potential along the channel and for the GNR-FET current-voltage characteristics (the depende…
The performance limits of the multilayer graphene nanoribbon (GNR) field-effect transistor (FET) are assessed and compared to those of monolayer GNR FET and carbon nanotube (CNT) FET. The results show that with a thin high-k gate insulator and reduced interlayer coupling, multilayer GNR FET can significantly outperform its CNT counterpart with a similar gate and bandgap in terms of the ballistic on-current. In the presence of optical phonon scattering, which has a short mean free path in the graphene-derived nanostructures, the advantage of the multilayer GNRFET is even more significant. The s…
In this work, we demonstrate atomic-layer-deposited (ALD) single-channel indium oxide (In2O3) gate-all-around (GAA) nanoribbon FETs in a back-end-of-line (BEOL) compatible process. A maximum on-state current (ION) of 19.3 mA/μm (near 20 mA/μm) is achieved in an In2O3 GAA nanoribbon FET with a channel thickness (TIO) of 3.1 nm, channel length (Lch) of 40 nm, channel width (Wch) of 30 nm and dielectric HfO2 of 5 nm. The record high drain current obtained from an In2O3 FET is about one order of magnitude higher than any conventional single-channel semiconductor FETs. This extraordinary drain curr…
Atomically precise graphene nanoribbons (GNRs) are increasingly attracting interest due to their largely modifiable electronic properties, which can be tailored by controlling their width and edge structure during chemical synthesis. In recent years, the exploitation of GNR properties for electronic devices has focused on GNR integration into field-effect-transistor (FET) geometries. However, such FET devices have limited electrostatic tunability due to the presence of a single gate. Here, we report on the device integration of 9-atom wide armchair graphene nanoribbons (9-AGNRs) into a multi-g…
Effects of phonon confinement on electron transport in Si nanowire and armchair-edge graphene nanoribbon transistors: A dissipative quantum-transport study
We have studied quantum transport in Graphene Nanoribbon Tunnel Field-Effect Transistors. Unlike other studies on similar structures, we have included dissipative processes induced by inelastic electron-phonon scattering and edge roughness in the nanoribbon self-consistently within a non-equilibrium transport simulation. Our results show that the dissipative scattering imposes a limit to the minimum OFF current and a minimum subthreshold swing that can be obtained even for long channel lengths where direct source-drain tunneling is inhibited. The edge roughness, in presence of dissipative scat…
The scaling behaviors of graphene nanoribbon (GNR) Schottky barrier field-effect transistors (SBFETs) are studied by solving the non-equilibrium Green's function (NEGF) transport equation in an atomistic basis set self-consistently with a three-dimensional Poisson equation. The armchair edge GNR channel shares similarities with a zigzag CNT, but it has a different geometry and quantum confinement boundary condition in the transverse direction. The results indicate that the I-V characteristics are ambipolar and strongly depend on the GNR width because the bandgap of the GNR is approximately inv…
One of severe limits of graphene nanoribbons (GNRs) in future applications is that zigzag GNRs (ZGNRs) are gapless, so cannot be used in field effect transistors (FETs). In this paper, using tight-binding approach and first principles method, we derived and proved a general edge (boundary) condition for the opening of a significant bandgap in ZGNRs with defective edge structures. The proposed semiconducting GNRs have some interesting properties including the one that they can be embedded and integrated in a large piece of graphene without the need of completely cutting them out. We also demons…
A large magnetoresistance effect is obtained at room-temperature by using p-i-n armchair-graphene-nanoribbon (GNR) heterostructures. The key advantage is the virtual elimination of thermal currents due to the presence of band gaps in the contacts. The current at B=0T is greatly decreased while the current at B>0T is relatively large due to the band-to-band tunneling effects, resulting in a high magnetoresistance ratio, even at room-temperature. Moreover, we explore the effects of edge-roughness, length, and width of GNR channels on device performance. An increase in edge-roughness and channel …
In recent past extensive device simulation work has already been done on TFETs. Various ways have been suggested to model TFETs. In our paper we look at one such particular way to model these devices. The Non equilibrium green's formalism has proved effective in modeling nano scale devices. We model complete SiGe and GaAs tunnel FET for the first time using the NEGF formalism, also taking acoustic phonon scattering into account. We analyze them on the grounds of I-V curve, Ion-Ioff ration and subthreshold slope. The poisson equation and the equilibrium statistical mechanical equation has been …
Van der Waal's heterostrucutures allow for novel devices such as two-dimensional-to-two-dimensional tunnel devices, exemplified by interlayer tunnel FETs. These devices employ channel/tunnel-barrier/channel geometries. However, during layer-by-layer exfoliation of these multi-layer materials, rotational misalignment is the norm and may substantially affect device characteristics. In this work, by using density functional theory methods, we consider a reduction in tunneling due to weakened coupling across the rotationally misaligned interface between the channel layers and the tunnel barrier. A…
We report on the experimental demonstration and electrical characterization of N = 7 armchair graphene nanoribbon (7-AGNR) field effect transistors. The back-gated transistors are fabricated from atomically precise and highly aligned 7-AGNRs, synthesized with a bottom-up approach. The large area transfer process holds the promise of scalable device fabrication with atomically precise nanoribbons. The channels of the FETs are approximately 30 times longer than the average nanoribbon length of 30 nm to 40 nm. The density of the GNRs is high, so that transport can be assumed well-above the percol…
A triple-heterojunction (3HJ) design is employed to improve p-type InAs/GaSb heterojunction (HJ) tunnel FETs. The added two HJs (AlInAsSb/InAs in the source and GaSb/AlSb in the channel) significantly shorten the tunnel distance and create two resonant states, greatly improving the ON state tunneling probability. Moreover, the source Fermi degeneracy is reduced by the increased source (AlInAsSb) density of states and the OFF state leakage is reduced by the heavier channel (AlSb) hole effective masses. Quantum ballistic transport simulations show, that with V_{DD} = 0.3V and I_{OFF} = 10^{-3}A/…
We study the electronic band structure and optical conductivity of an array of tunnel-coupled array of graphene nanoribbons. We show that due to the coupling of electronic edge states for the zigzag nanoribbon structure, the Fermi surface can become a hyperbola similarly to the case of the layered metal-dielectric structures, where the hyperbolic isofrequency contours originate from the coupling of localized surface plasmon polaritons. Moreover, we show that for both types of the ribbon edge, the optical response of the structure can be characterized by a uniaxial conductivity tensor, having p…
Bottom-up synthesized GNRs and GNR heterostructures have promising electronic properties for high performance field effect transistors (FETs) and ultra-low power devices such as tunnelling FETs. However, the short length and wide band gap of these GNRs have prevented the fabrication of devices with the desired performance and switching behaviour. Here, by fabricating short channel (Lch ~20 nm) devices with a thin, high-k gate dielectric and a 9-atom wide (0.95 nm) armchair GNR as the channel material, we demonstrate FETs with high on-current (Ion >1 uA at Vd = -1 V) and high Ion/Ioff ~10^5 at …
In recent part extensive simulation work has already been done on TFETs. However this is limited to device performance analysis. Evaluation of circuit performance is a topic that is very little touched. This is due to the non availability of compact models of Tunnel FETs in the commercial simulator. In our paper for the first time we perform the circuit analysis of tunnel FETs (extended channel TFETs), we test them over basic digital circuit. We generate the TFET models by using the model editor in Orcad. Extensive circuit simulation is then performed by using these models in the Pspice circui…
In this paper, we have worked out a pseudo two dimensional (2D) analytical model for surface potential and drain current of a long channel p-type Dual Material Gate (DMG) Gate All-Around (GAA) nanowire Tunneling Field Effect Transistor (TFET). The model incorporates the effect of drain voltage, gate metal work functions, thickness of oxide and silicon nanowire radius. The model does not assume a fully depleted channel. With the help of this model we have demonstrated the accumulation of charge at the interface of the two gates. The accuracy of the model is tested using the 3D device simulator …
A real-space quantum transport simulator for carbon nanoribbon (CNR) MOSFETs has been developed. Using this simulator, the performance of carbon nanoribbon (CNR) MOSFETs is examined in the ballistic limit. The impact of quantum effects on device performance of CNR MOSFETs is also studied. We found that 2D semi-infinite graphene contacts provide metal-induced-gap-states (MIGS) in the CNR channel. These states would provide quantum tunneling in the short channel device and cause Fermi level pining. These effects cause device performance degradation both on the ON-state and the OFF-state. Pure 1D…
A bilayer graphene based electrostatically doped tunnel field-effect transistor (BED-TFET) is proposed in this work. Unlike graphene nanoribbon TFETs in which the edge states deteriorate the OFF-state performance, BED-TFETs operate based on different bandgaps induced by vertical electric fields in the source, channel, and drain regions without any chemical doping. The performance of the transistor is evaluated by self-consistent quantum transport simulations. This device has several advantages: 1) ultra-low power (VDD=0.1V), 2) high performance (ION/IOFF>104), 3) steep subthreshold swing (SS<1…
We study the transport property for armchair-edge graphene nanoribbons (AGNRs) with an adatom coupling to a semi-infinite quantum wire. Using the nonequilibrium Green's function approach with tight-binding approximation, we demonstrate that the tunneling current through the system is sensitively dependent on both the AGNR width and adatom location. Interestingly, when the adatom locates onto a carbon atom in the 3$j$th chain from the edge of a metallic AGNR, the system shows a transmission gap accompanied by a threshold voltage in $I-V$ curve like a semiconducting AGNR. This effect may be usef…
Vertical tunneling field-effect-transistor (FET) based on graphene heterojunctions with layers of hBN is simulated by self-consistent quantum transport simulations. It is found that the asymmetric p-type and n-type conduction is due to work function deference between the graphene contact and the tunneling channel material. Modulation of the bottom-graphene-contact plays an important role in determining the switching characteristic of the device. Due to the electrostatic short-channel-effects stemming from the vertical-FET structure, the output I-V characteristics do not saturate. The scaling b…
In this paper, we present a mode space method for atomistic non-equilibrium Green's function simulations of armchair graphene nanoribbon FETs that includes electron-phonon scattering. With reference to both conventional and tunnel FET structures, we show that, in the ideal case of a smooth electrostatic potential, the modes can be decoupled in different groups without any loss of accuracy. Thus, inter-subband scattering due to electron-phonon interactions is properly accounted for, while the overall simulation time considerably improves with respect to real-space, with a speed-up factor of 40 …
We present a compact model for Tunnel Field Effect Transistors (TFET), that captures sev- eral non-idealities such as the Trap Assisted Tunneling (TAT) originating from interface traps (Dit), along with Verilog-A implementation. We show that the TAT, together with band edge non-abruptness known as the Urbach tail, sets the lower limit of the sub-threshold swing and the minimum achievable current at a given temperature. Presence of charged trap states also contributes to reduced gate efficiency. We show that we can decouple the contribution of each of these processes and extract the intrinsic s…
In this work, we propose the Bilayer Graphene Tunnel Field Effect Transistor (BG-TFET) as a device suitable for fabrication and circuit integration with present-day technology. It provides high Ion/Ioff ratio at ultra-low supply voltage, without the limitations in terms of prohibitive lithography and patterning requirements for circuit integration of graphene nanoribbons. Our investigation is based on the solution of the coupled Poisson and Schroedinger equations in three dimensions, within the Non-Equilibrium Green (NEGF) formalism on a Tight Binding Hamiltonian. We show that the small achiev…
Full-band atomistic quantum transport simulations based on first principles are employed to assess the potential of band-to-band tunneling FETs (TFETs) with a 2-D channel material as future electronic circuit components. We demonstrate that single-layer (SL) transition metal dichalcogenides are not well suited for TFET applications. There might, however, exist a great variety of 2-D semiconductors that have not even been exfoliated yet; this paper pinpoints some of the most promising candidates among them to realize highly efficient TFETs. SL SnTe, As, TiNBr, and Bi are all found to ideally de…
GaSb/InAs heterojunction tunnel field-effect transistors are strong candidates in building future low-power integrated circuits, as they could provide both steep subthreshold swing and large ON-state current ($I_{\rm{ON}}$). However, at short channel lengths they suffer from large tunneling leakage originating from the small band gap and small effective masses of the InAs channel. As proposed in this article, this problem can be significantly mitigated by reducing the channel thickness meanwhile retaining a thick source-channel tunnel junction, thus forming a design with a non-uniform body thi…
The band-to-band tunneling transistors have some performance advantages over the conventional MOSFETs due to the <60mV/dec sub-threshold slope. In this paper, carbon nanotubes are used as a model channel material to address issues that we believe will apply to BTBT FETs vs. MOSFETs more generally. We use pz-orbital tight-binding Hamiltonian and the non-equilibrium Green function (NEGF) formalism for rigorous treatment of dissipative quantum transport. A device level comparison of p-i-n TFETs and n-i-n MOSFETs in both ballistic and dissipative cases has been performed previously. In this paper,…
By using first-principles calculations, we predict that an in-plane homogenous electrical field can induce half-metallicity in hydrogen-terminated zigzag silicene and germanene nanoribbons (ZSiNRs and ZGeNRs). A dual-gated finite ZSiNR device reveals a nearly perfect spin-filter efficiency of up to 99% while a quadruple-gated finite ZSiNR device serves as an effective spin field effect transistor (FET) with an on/off current ratio of over 100 from ab initio quantum transport simulation. This discovery opens up novel prospect of silicene and germanene in spintronics.
We theoretically investigate the spin-charge transport in two-terminal device of graphene nanoribbons in the presence of an uniform uniaxial strain, spin-orbit coupling, exchange field and smooth staggered potential. We show that the direction of applied strain can efficiently tune strain-strength induced oscillation of band-gap of armchair graphene nanoribbon (AGNR). It is also found that electronic conductance in both AGNR and zigzag graphene nanoribbons (ZGNRs) oscillates with Rashba spin-orbit coupling akin to the Datta-Das field effect transistor. Two distinct strain response regimes of e…
One-dimensional diffusion of Co ad-atoms on graphene nanoribbons has been induced and investigated by means of scanning tunnelling microscopy (STM). To this end, the nanoribbons and the Co ad-atoms have been imaged before and after injecting current pulses into the nanoribbons, with the STM tip in direct contact with the ribbon. We observe current-induced motion of the Co atoms along the nanoribbons, which is approximately described by a distribution expected for a thermally activated one-dimensional random walk. This indicates that the nanoribbons reach temperatures far beyond 100 K, which is…
Graphene has shown impressive properties for nanoelectronics applications including a high mobility and a width-dependent bandgap. Use of graphene in nanoelectronics would most likey be in the form of graphene nanoribbons (GNRs) where the ribbon width is expected to be less than 20 nm. Many theoretical projections have been made on the impact of edge-scattering on carrier transport in GNRs - most studies point to a degradation of mobility (of GNRs) as well as the on/off ratio (of GNR FETs). This study provides the first clear experimental evidence of the onset of size-effect in patterned GNRs;…
The practical realization of nano-scale electronics faces two major challenges: the precise engineering of the building blocks and their assembly into functional circuits. In spite of the exceptional electronic properties of carbon nanotubes only basic demonstration-devices have been realized by time-consuming processes. This is mainly due to the lack of selective growth and reliable assembly processes for nanotubes. However, graphene offers an attractive alternative. Here we report the patterning of graphene nanoribbons (GNRs) and bent junctions with nanometer precision, well-defined widths a…
We numerically investigate the possibility of using Tunnel field-effect transistor (TFET) in a 32 kHz crystal oscillator circuit to reduce power consumption. A simulation using SPICE (Simulation Program with Integrated Circuit Emphasis) is carried out based on a conventional CMOS transistor model. It is shown that the power consumption of TFET is one-tenth that of conventional low-power CMOS.
We study the edge magnetization and the local density of states of chiral graphene nanoribbons using a π-orbital Hubbard model in the mean-field approximation. We show that the inclusion of a realistic next-nearest hopping term in the tight-binding Hamiltonian changes the graphene nanoribbons band structure significantly and affects its magnetic properties. We study the behavior of the edge magnetization upon departing from half filling as a function of the nanoribbon chirality and width. We find that the edge magnetization depends very weakly in the nanoribbon width, regardless of chirality a…
With nonequilibrium Green's function approach combined with density functional theory, we perform an ab initio calculation to investigate transport properties of graphene nanoribbon junctions self-consistently. Tight-binding approximation is applied to model the zigzag graphene nanoribbon (ZGNR) electrodes, and its validity is confirmed by comparison with GAUSSIAN03 PBC calculation of the same system. The origin of abnormal jump points usually appearing in the transmission spectrum is explained with the detailed tight-binding ZGNR band structure. Transport property of an edge defect ZGNR junct…
Floating gate transistor is the basic building block of non-volatile flash memory, which is one of the most widely used memory gadgets in modern micro and nano electronic applications. Recently there has been a surge of interest to introduce a new generation of memory devices using graphene nanotechnology. In this paper we present a new floating gate transistor (FGT) design based on multilayer graphene nanoribbon (MLGNR) and carbon nanotube (CNT). In the proposed FGT a multilayer structure of graphene nanoribbon (GNR) would be used as the channel of the field effect transistor (FET) and a laye…
We investigate the role of various structural nonidealities on the performance of armchair-edge graphene nanoribbon field effect transistors (GNRFETs). Our results show that edge roughness dilutes the chirality dependence often predicted by theory but absent experimentally. Instead, GNRs are classifiable into wide (semi-metallic) vs narrow (semiconducting) strips, defining thereby the building blocks for wide-narrow-wide all-graphene devices and interconnects. Small bandgaps limit drain bias at the expense of band-to-band tunneling in GNRFETs. We outline the relation between device performance…
We investigate chiral graphene nanoribbons using projective quantum Monte Carlo simulations within the local Hubbard model description and study the effects of electron-electron interactions on the electronic and magnetic properties at the ribbon edges. Static and dynamical properties are analyzed for nanoribbons of varying width and edge chirality, and compared to a self-consistent Hartee-Fock mean-field approximation. Our results show that for chiral ribbons of sufficient width, the spin correlations exhibit exceedingly long correlation lengths, even between zigzag segments that are well sep…
The impact of electrostatic doping level on the dissipative transport of Armchair GNR-TFET is studied using the Quantum Perturbation Theory (QPT) with the Extended Lowest Order Expansion (XLOE) implementation method. Results show that the doping level of the source and drain sides of the GNR-TFET has a significant impact on the phonon contribution to the carrier transport process. Unlike in other similar studies, where phonons are believed to have a constant detrimental influence on the ION/IOFF ratio and Subthreshold Swing (SS) of the TFET devices due to the phonon absorption-assisted tunneli…
Topological insulator (TI) nanoribbons with proximity-induced superconductivity are a promising platform for Majorana bound states (MBSs). In this work, we consider a detailed modeling approach for a TI nanoribbon in contact with a superconductor via its top surface, which induces a superconducting gap in its surface-state spectrum. The system displays a rich phase diagram with different numbers of end-localized MBSs as a function of chemical potential and magnetic flux piercing the cross section of the ribbon. These MBSs can be robust or fragile upon consideration of electrostatic disorder. W…
We explore the device potential of tunable-gap bilayer graphene FET exploiting the possibility of opening a bandgap in bilayer graphene by applying a vertical electric field via independent gate operation. We evaluate device behavior using atomistic simulations based on the self-consistent solution of the Poisson and Schroedinger equations within the NEGF formalism. We show that the concept works, but bandgap opening is not strong enough to suppress band-to-band tunneling in order to obtain a sufficiently large Ion/Ioff ratio for CMOS device operation.
The success of graphene for nanopore DNA sequencing has shown that it is possible to explore other potential single-atom and few-atom thick layers of elemental 2D materials beyond graphene (e.g., phosphorene and silicene). Using density functional theory, we studied the interaction of DNA bases with nanopores created in finite-size nanoribbons from graphene, phosphorene, and silicene. We observe that binding energies of DNA bases using nanopores from phosphorene and silicene are generally smaller compared to graphene. The band gaps of phosphorene and silicene are significantly altered due to i…
We argue that twisted graphene nanoribbons subjected to a transverse electric field can operate as a variety of nanoelectronic devices, such as tunable tunnel diodes with current-voltage characteristics controlled by the transverse field. Using the density-functional tight-binding method to address the effects of mechanical strain induced by the twisting, we show that the electronic transport properties remain almost unaffected by the strain in relevant cases and propose a simplified tight-binding model which gives reliable results. The transverse electric field creates a periodic electrostati…
We investigate a two-dimensional (2D) heterostructure consisting of few-layer direct bandgap ReS2, a thin h-BN layer and a monolayer graphene for application to various electronic devices. Metal-insulator-semiconductor (MIS)-type devices with two-dimensional (2D) van-der-Waals (vdW) heterostructures have recently been studied as important components to realize various multifunctional device applications in analogue and digital electronics. The tunnel diodes of ReS2/h-BN/graphene exhibit light tuneable rectifying behaviours with low ideality factors and nearly temperature independent electrical…
The edges of graphene nanoribbons (GNRs) have attracted much interest due to their potentially strong influence on GNR electronic and magnetic properties. Here we report the ability to engineer the microscopic edge termination of high quality GNRs via hydrogen plasma etching. Using a combination of high-resolution scanning tunneling microscopy and first-principles calculations, we have determined the exact atomic structure of plasma-etched GNR edges and established the chemical nature of terminating functional groups for zigzag, armchair and chiral edge orientations. We find that the edges of …
A weakly coupled system of two crossed graphene nanoribbons exhibits direct tunneling due to the overlap of the wavefunctions of both ribbons. We apply the Bardeen transfer Hamiltonian formalism, using atomistic band structure calculations to account for the effect of the atomic structure on the tunneling process. The strong quantum-size confinement of the nanoribbons is mirrored by the one-dimensional character of the electronic structure, resulting in properties that differ significantly from the case of inter-layer tunneling, where tunneling occurs between bulk two-dimensional graphene shee…
Recent theoretical calculations and photoemission spectroscopy measurements on the bulk Bi2Se3 material show that it is a three-dimensional topological insulator possessing conductive surface states with nondegenerate spins, attractive for dissipationless electronics and spintronics applications. Nanoscale topological insulator materials have a large surface-to-volume ratio that can manifest the conductive surface states and are promising candidates for devices. Here we report the synthesis and characterization of high quality single crystalline Bi2Se3 nanomaterials with a variety of morpholog…
Graphene nanoribbons (GNRs) are a family of one-dimensional (1D) materials carved from graphene lattice. GNRs possess high mobility and current carrying capability, sizable bandgap, and versatile electronic properties tailored by the orientations and open edge structures. These unique properties make GNRs promising candidates for prospective electronics applications including nano-sized field-effect transistors (FETs), spintronic devices, and quantum information processing. To fully exploit the potential of GNRs, fundamental understanding of structure-property relationship, precise control of …
