Tunable Negative Differential Resistance in van der Waals Heterostructures at Room Temperature by Tailoring the Interface

Abstract

Vertically stacked two-dimensional van der Waals (vdW) heterostructures, used to obtain homogeneity and band steepness at interfaces, exhibit promising performance for band-to-band tunneling (BTBT) devices. Esaki tunnel diodes based on vdW heterostructures, however, yield poor current density and peak-to-valley ratio, inferior to those of three-dimensional materials. Here, we report the negative differential resistance (NDR) behavior in a WSe2/SnSe2 heterostructure system at room temperature and demonstrate that heterointerface control is one of the keys to achieving high device performance by constructing WSe2/SnSe2 heterostructures in inert gas environments. While devices fabricated in ambient conditions show poor device performance due to the observed oxidation layer at the interface, devices fabricated in inert gas exhibit extremely high peak current density up to 1460 mA/mm2, 3–4 orders of magnitude higher than reported vdW heterostructure-based tunnel diodes, with a peak-to-valley ratio of more than 4 at room temperature. Besides, Pd/WSe2 contact in our device possesses a much higher Schottky barrier than previously reported Cr/WSe2 contact in the WSe2/SnSe2 device, which suppresses the thermionic emission current to less than the BTBT current level, enabling the observation of NDR at room temperature. Diode behavior can be further modulated by controlling the electrostatic doping and the tunneling barrier as well.

Tailoring Quantum Tunneling in a Vanadium‐Doped WSe2/SnSe2 Heterostructure

“…As the negative gate bias increases, the rectification ratio degrades in the forward direction but is improved in the backward diode. The peak‐to‐valley ratio is inversely proportional to the gate bias with a maximum value of 2.3, especially with 4% V‐WSe 2 , higher than the value of 1.8 obtained from the WSe 2 /SnSe 2 without h‐BN insulating layer . This is ascribed to the increase in available energy states for tunneling, modulated by the high V‐doping concentration.…”

“…Meanwhile, the peak-to-valley ratio in NDR diode rises up to 2.3 at V G = −110 V (Figure 4c). [26] This is ascribed to the increase in available energy states for tunneling, modulated by the high V-doping concentration. Figure 4d summarizes the improved device performances in terms of the rectification ratio (forward and backward) and peak-to-valley ratio with the gate bias modulation.…”

Programmable Organic‐Free Negative Differential Resistance Memristor Based on Plasmonic Tunnel Junction

“…Negative differential resistance (NDR) effect is promising for electronics due to the special electronic performance of a decrease in current in response to an increase in the bias voltage, [1,2] which is compatible with integrated circuits and provides good logic functionality for memristors. [3,4] Since the first report on NDR effect in narrow germanium P-N Junctions by Esaki in 1958, [5] NDR effect has been observed and extended, for instance, in tunneling molecular electronic devices, [1,6] van der Waals heterostructures, [7] graphene transistors, [8] nanoscale metal-oxide-metal heterojunction system [9] or metal-insulatormetal diodes, [10] and conducting polymer-encapsulated gold nano particles (AuNPs)-based memristors. [11][12][13] Most of the studies have illustrated the key role of molecular and chemical (or semiconductor) properties of active components of tunneling A novel negative differential resistance (NDR) phenomenon is reported herein based on planar plasmonic tunnel junction, resulting from plasmonassisted long-range electron tunneling (P-tunneling) and electronic caching effect of Au@SiO 2 nanoparticles.…”

Low‐Power Complementary Inverter with Negative Capacitance 2D Semiconductor Transistors

“…exhibit n‐type characteristics, because dichalcogenides vacancies act as n‐type dopant. [ 21–28 ] Even for tungsten diselenide (WSe 2 ) with balanced conduction and valence band edges, it usually exhibits ambipolar transport characteristics without doping. [ 2,5,8,29 ] Thus, it is of great importance to fabricate unipolar p‐type TMD semiconductors FETs to achieve complementary NCFET in a controllable manner.…”