Analog Circuit Applications Based on All‐2D Ambipolar ReSe₂ Field‐Effect Transistors

Abstract

Complementary circuits based on 2D materials show great promise for nextgeneration electronics. An ambipolar all-2D ReSe 2 field-effect transistor (FET) with a hexagonal boron nitride gate dielectric is fabricated and its electronic characteristics are comprehensively studied by temperature dependence and noise measurements. Ambipolar transfer characteristics are achieved owing to the tunable Fermi level of the graphene contact and negligible and 30 meV Schottky barrier heights for the n-and p-channel regimes, respectively. An inverter is also fabricated to demonstrate ambipolar ReSe 2 FET operation in a logic circuit. Furthermore, a p/n switchable unipolar FET is designed and shows potential for building complimentary circuits from a signal device. This work demonstrates the potential of all-2D ReSe 2 FETs and makes available new approaches for designing next-generation devices.

Highly crystalline ReSe2 atomic layers synthesized by chemical vapor transport

“…The electrical performance of the FETs was measured at room temperature in vacuum (<10 −4 Pa) and the ReSe 2 devices exhibited n‐type conduction with an on/off current ratio up to 10 5 (Figure B). The electron mobility of the ReSe 2 device shown in Figure B was estimated to be ∼5.0 cm 2 V −1 s −1 , which is comparable to the mechanically‐exfoliated flakes and superior to CVD‐grown ReSe 2 (Figure C,D), confirming the very high quality of our CVT‐grown samples. The improvement of the mobility can be attributed to the use of Re and Se powder as source materials and the slow growth process under high temperature and high vacuum in comparison with conventional CVD growth.…”

“…Two-dimensional (2D) rhenium diselenide (ReSe 2 ) is an emerging anisotropic transition metal dichalcogenides (TMDCs) in distorted 1T 0 structure with triclinic symmetry. [1][2][3][4] This structure endows ReSe 2 with many unusual properties, such as weak interlayer coupling and strong in-plane anisotropic optical, 3 electrical, 1,3 and phonon 2 properties and therefore, exhibits great potential for applications in logic inverters, 5 polarizationsensitive photodetectors, 3 and so on. However, the fundamental investigations and the fabrication of proof-of-concept devices on ReSe 2 are highly-relied on 2D flakes mechanically exfoliated from the bulk crystals synthesized via chemical vapor transport (CVT) [5][6][7] method, which does not allow for the controllable and high-throughput preparation.…”

“…[1][2][3][4] This structure endows ReSe 2 with many unusual properties, such as weak interlayer coupling and strong in-plane anisotropic optical, 3 electrical, 1,3 and phonon 2 properties and therefore, exhibits great potential for applications in logic inverters, 5 polarizationsensitive photodetectors, 3 and so on. However, the fundamental investigations and the fabrication of proof-of-concept devices on ReSe 2 are highly-relied on 2D flakes mechanically exfoliated from the bulk crystals synthesized via chemical vapor transport (CVT) [5][6][7] method, which does not allow for the controllable and high-throughput preparation. Recently, the direct synthesis of 2D ReSe 2 has been explored through chemical vapor deposition (CVD), 1,[8][9][10][11] however, the mobility of the CVD-grown samples is obviously lower than their mechanically exfoliated counterparts 1,2,8-10 (0.25 cm 2 V −1 s −1 vs 4 cm 2 V −1 s −1 ).…”

Probing Charge Transport Difference in Parallel and Vertical Layered Electronics with Thin Graphite Source/Drain Contacts

“…Previous authors have already demonstrated the existence of a Schottky barrier at the interface of the metal and the layered material, where charge carriers overcome this barrier at higher temperatures and show thermally-assisted tunnelling at lower temperatures 7 . However, it has now been experimentally proven that the small work function difference between graphene and layered materials allows graphene as a transistor contact to reduce the contribution of contact resistance and then form an Ohmic contact, achieving superior device performance 10–14 . Recently, these transistors with layered conducting channels connected in-plane have been surpassed by van der Waals heterostructures, formed by the layer-by-layer integration of various 2D materials in the vertical direction.…”

“…Recently, these transistors with layered conducting channels connected in-plane have been surpassed by van der Waals heterostructures, formed by the layer-by-layer integration of various 2D materials in the vertical direction. This development has opened a whole new class of materials in condensed matter physics, some of which are being recognized as building blocks for the framework of novel three-dimensional (3D) artificial structures 14–18 . Pioneering achievements using these vertically stacked heterostructures have been demonstrated in diverse applications, such as logic devices 19 , atomically thin p-n junctions 20 , van der Waals memristors 21 , tunnelling transistors 22 , and even multifunctional electronics 17,19,23 .…”