Negative Differential Resistance in Boron Nitride Graphene Heterostructures: Physical Mechanisms and Size Scaling Analysis

Abstract

Hexagonal boron nitride (hBN) is drawing increasing attention as an insulator and substrate material to develop next generation graphene-based electronic devices. In this paper, we investigate the quantum transport in heterostructures consisting of a few atomic layers thick hBN film sandwiched between graphene nanoribbon electrodes. We show a gate-controllable vertical transistor exhibiting strong negative differential resistance (NDR) effect with multiple resonant peaks, which stay pronounced for various device dimensions. We find two distinct mechanisms that are responsible for NDR, depending on the gate and applied biases, in the same device. The origin of first mechanism is a Fabry-Pérot like interference and that of the second mechanism is an in-plane wave vector matching when the Dirac points of the electrodes align. The hBN layers can induce an asymmetry in the current-voltage characteristics which can be further modulated by an applied bias. We find that the electron-phonon scattering suppresses the first mechanism whereas the second mechanism remains relatively unaffected. We also show that the NDR features are tunable by varying device dimensions. The NDR feature with multiple resonant peaks, combined with ultrafast tunneling speed provides prospect for the graphene-hBN-graphene heterostructure in the high-performance electronics.

Sub-bandgap Voltage Electroluminescence and Magneto-oscillations in a WSe2 Light-Emitting van der Waals Heterostructure

“…To this end one has to rely both on the theoretical estimations 17,18 and on the spectroscopic experimental works targeting these band offsets. 3,5,19 A schematic illustration of the bands is shown in Figure 1 By using the proposed band alignment scenario, we can divide the differential conductance (Figure 1 (c)) in three distinct tunneling regimes. The first one occurs at around zero bias, where a pronounced peak is observed.…”

“…To this end one has to rely both on the theoretical estimations 17,18 and on the spectroscopic experimental works targeting these band offsets. 3,5,19 A schematic illustration of the bands is shown in Figure 1 and graphene has been recently studied using µ-ARPES and an offset of 0.70 eV between the Dirac point and the WSe 2 valence band edge has been reported. 19 Assuming a direct band gap for monolayer WSe 2 of about 2 − 2.2 eV 20,21 one can conclude that the energy separation between the Dirac point of graphene and the valence band edge of WSe 2 should be significantly lower as compared to the conduction band.…”

Nested dissection solver for transport in 3D nano-electronic devices

“…The system Hamiltonian is constructed using the nearest neighbor tight binding approximation with parameters from [27]. Only the low energy p z orbitals are considered here; thus the Hamiltonian has the same dimension as the total number of atoms simulated.…”

Простые Модели Латеральных Гетероструктур

“…В меньшей степени внимание уделяется лате-ральным структурам, образованным состыкованными по кромкам 2D-слоями, расположенными в одной плоско-сти [3,5,6]. Отметим, что наиболее популярны ГС, где компонентами является графен и гексагональный нитрид бора (h-BN), причем как для вертикального [4,7,8], так и для латерального [6,9,10] вариантов.В настоящей работе мы предложим схему описания электронной структуры латеральных ГС, основанную на методе функций Грина и теории сильной связи. При этом для простоты будут рассмотрены модели контактов одноатомных и двухатомных квадратных ре-шеток с одинаковыми расстояниями между ближайшими соседями (б.с.…”