Ultrahigh ON/Off Current Ratio γ-Graphyne-1 Nanotube Based Sub 10 nm TFET Modeling and Simulation

Utilizing γ-graphyne-1 nanotubes (GyNTs) in the Tunneling Field Effect Transistors (TFETs) suppresses ambipolarity and enhances subthreshold swing (SS) of TFETs which is because of large energy band gap and high electron effective mass of GyNTs. In this research analysis of structural, electronic and thermoelectric properties of γ-graphyne-1 family under the deformation potential (DP) approach reveals that electron-phonon mean free path (MFP) of an Armchair GyNT (3AGyNT) and Zigzag GyNT (2ZGyNT) are 45 and 290 nm, respectively. Therefore, ballistic transport of sub 10 nm 3AGyNT-TFETs and 2ZGyNT-TFETs in different channel lengths are investigated utilizing Non-Equilibrium Green’s Function (NEGF) formalism in the DFTB platform. Ultrahigh Current Ratio (OOCR) value of 1.6 x 1010 at VDD = 0.2 V and very low point SS of 5 mV/dec are belonged to the 3AGyNT-TFET with channel length of 9.6 nm. 2ZGyNT-TFETs shows higher on-state current and SS as well as lower OOCR than those of 3AGyNT-TFETs. A linear relationship between channel length and logarithmic off-state current is reported that is consistent with WKB approximation. The obtained results along with the ultralow power consumption of the suggested GyNT-TFETs, make them as replacement of digital silicon MOSFETs in the next generation nanoelectronic devices.

Carbon-Based Micro/Nano Devices for Transistors, Sensors, and Memories

The ballistic transport of electrons and unique structural characteristics of graphene and carbon nanotubes enable them to play an important role in nano electronical appliances. Nanodevices based on carbon nano materials can further reduce device size without affecting performance. Here, this paper analyzes Fin Field-effect transistor (FinFET) and Tunnel Field-effect transistor (TFET) based on graphene nanoribbon (GNR) and carbon nanotube which could be used for reducing power consumption. Then it summarizes the applications of graphene in micro/nano sensors based on the electrical, mechanical, optical, and thermal properties of graphene. Graphene’s single-atom thickness and charge storage mechanism provide itself with great potential in the field of resistive memory. Graphene is also widely used in flexible electronic devices.

Energy transport in Z3 chiral clock model

We characterize the energy transport in a one dimensional Z3 chiral clock model. The model generalizes the Z2 symmetric transverse field Ising model (TFIM). The model is parametrized by a chirality parameter Θ, in addition to f and J which are analogous to the transverse field and the nearest neighbour spin coupling in the TFIM. Unlike the well studied TFIM and XYZ models, does not transform to a fermionic system. We use a matrix product states implementation of the Lindblad master equation to obtain the non-equilibrium steady state (NESS) in systems of sizes up to 48. We present the estimated NESS current and its scaling exponent γ as a function of Θ at different f/J. The estimated γ(f/J,Θ) point to a ballistic energy transport along a line of integrable points f=Jcos{3Θ} in the parameter space; all other points deviate from ballistic transport. Analysis of finite size effects within the available system sizes suggest a diffusive behavior away from the integrable points.

Atomistic Simulation of Ultra-Short Pulsed Laser Ablation of Al: An Extension for Non-Thermalized Electrons and Ballistic Transport

For our model material aluminum, the influence of the laser pulse duration in the range between 0.5 ps and 16 ps on the ablation depth is investigated in a computational study with a hybrid approach, combining molecular dynamics with the well known two-temperature model. A simple, yet expedient extension is proposed to account for the delayed thermalization as well as ballistic transport of the excited electrons. Comparing the simulated ablation depths to a series of our own experiments, the extension is found to considerably increase the predictive power of the model.

Low-symmetry nonlocal transport in microstructured squares of delafossite metals

Intense work studying the ballistic regime of electron transport in two-dimensional systems based on semiconductors and graphene had been thought to have established most of the key experimental facts of the field. In recent years, however, additional forms of ballistic transport have become accessible in the quasi–two-dimensional delafossite metals, whose Fermi wavelength is a factor of 100 shorter than those typically studied in the previous work and whose Fermi surfaces are nearly hexagonal in shape and therefore strongly faceted. This has some profound consequences for results obtained from the classic ballistic transport experiment of studying bend and Hall resistances in mesoscopic squares fabricated from delafossite single crystals. We observe pronounced anisotropies in bend resistances and even a Hall voltage that is strongly asymmetric in magnetic field. Although some of our observations are nonintuitive at first sight, we show that they can be understood within a nonlocal Landauer-Büttiker analysis tailored to the symmetries of the square/hexagonal geometries of our combined device/Fermi surface system. Signatures of nonlocal transport can be resolved for squares of linear dimension of nearly 100 µm, approximately a factor of 15 larger than the bulk mean free path of the crystal from which the device was fabricated.

Asymmetric bias-induced barrier lowering as an alternative origin of current rectification in geometric diodes

Geometric diodes, which take advantage of geometric asymmetry to achieve current flow preference, are promising for THz current rectification. Previous studies relate geometric diodes’ rectification to quantum coherent or ballistic transport, which is fragile and critical of the high-quality transport system. Here we propose a different physical mechanism and demonstrate a robust current rectification originating from the asymmetric bias induced barrier lowering, which generally applies to common semiconductors in normal environments. Key factors to the diode’s rectification are carefully analyzed, and an intrinsic rectification ability at up to 1.1 THz is demonstrated.