Alloyed 2D Metal–Semiconductor Atomic Layer Junctions

Abstract

Heterostructures of compositionally and electronically variant two-dimensional (2D) atomic layers are viable building blocks for ultrathin optoelectronic devices. We show that the composition of interfacial transition region between semiconducting WSe2 atomic layer channels and metallic NbSe2 contact layers can be engineered through interfacial doping with Nb atoms. WxNb1-xSe2 interfacial regions considerably lower the potential barrier height of the junction, significantly improving the performance of the corresponding WSe2-based field-effect transistor devices. The creation of such alloyed 2D junctions between dissimilar atomic layer domains could be the most important factor in controlling the electronic properties of 2D junctions and the design and fabrication of 2D atomic layer devices.

Charge carrier injection and transport engineering in two-dimensional transition metal dichalcogenides

“…1 ). 104 More interestingly, graphene as a face-contact material can reduce R C dynamically by pumping charge via band alignment modulation. 105 On the other hand, edge-contact devised by atomically sharp interfaces strongly reduces the FLP and enables control over the SB.…”

High-quality monolayer superconductor NbSe2 grown by chemical vapour deposition

“…Recently, NbSe 2 multilayers were prepared by selenizing pre-deposited Nb 2 O 5 films. However, none of the prepared NbSe 2 was found to be superconducting 25 , 26 , probably due to the large concentration of defects created during growth. Currently, superconducting NbSe 2 monolayers can only be grown by molecular beam epitaxial (MBE) under ultrahigh vacuum (UHV) and on a dangling bond-free graphene or h -BN substrate 3 , 27 , in order to minimize environment- and substrate-induced disorders/defects.…”

Artificial 2D van der Waals Synapse Devices via Interfacial Engineering for Neuromorphic Systems

“…Holes are known to be the major carriers in both the semiconductor chann To elucidate the origin of the hysteresis of the 2D heterostructure transistors, the corresponding energy band model was proposed (Figure 4). We previously reported the positive effect of the combination of WSe 2 -NbSe 2 with reduced contact barrier [24,25]. The conventional Richardson-Schottky equation was employed to calculate Schottky barrier,…”

“…Then, the synthesized WSe 2 semiconducting channel was transferred onto an SiO 2 /Si wafer using a poly(methyl methacrylate)-assisted transfer method and patterned using conventional photolithography. Finally, the NbSe 2 metallic electrode was transferred for the formation of the NbSe 2 /WSe 2 van der Waals heterojunction, in order to minimize the contact resistance [24,25].…”

“…Here, WSe 2 and Nb 2 O 5 served as the active channel, and the conductance-tuning layer, respectively. Additionally, the NbSe 2 electrode can provide excellent transistor switching characteristics due to a sharp 2D interface and the absence of the metal-induced gap states [24,25]. The post-synaptic current behavior can be modulated precisely by adjusting the thickness of the Nb 2 O 5 layer, with a thicker Nb 2 O 5 interlayer providing higher synapse spike current and strong interaction in paired pulse facilitation testing modes.…”