Ohmic Contact in 2D Semiconductors via the Formation of a Benzyl Viologen Interlayer

Abstract

The fabrication of a polymeric Ohmic contact interlayer between a metal and a 2D material using solution-processed benzyl viologen (BV) is reported here. Predoping of the polymer alters the contact surface to obtain electrondoped materials with ultrahigh work functions that significantly enhance the current density across the contact and reduce the contact resistance and Schottky barrier height. The fabrication of solution-processed polymeric contacts for the preparation of high mobility MoS 2 , WSe 2 , MoTe 2 , and BP (black phosphorous) FETs with significantly lowered contact resistance is demonstrated. Ohmic contacts are achieved and produce 3-, 700-, 3000-, and 17-fold increases in electron mobilities, respectively, when the bottom gate voltage is 10 V compared to those respective materials alone. Ambipolar and p-type 2D material based FETs could, therefore, be transformed into n-type FETs. Most importantly, the devices exhibit excellent stability in both ambient and vacuum.

Direct observation of contact resistivity for monolayer TMD based junctions via PL spectroscopy

“…Obviously, the former was comparable to the optimal values (∼123 Ω μm) of the latter that was measured in Bi/MoS 2 structures with zero-Schottky barrier component. 6,7,35,[43][44][45][46][47][48][49][50][51][52][53][54][55][56][57] These ultralow contact resistances confirm the claim that in our case it does not contain the Schottky barrier component. The contact resistance of 1 L MoSe 2 /Au was further measured by the gFPP method (Fig.…”

Semi-Metal Edge Contact for Barrier-Free Carrier Transport in MoS2 Field Effect Transistors

“…For a more comprehensive comparison, we compiled the previous reports about achieving MoS 2 ohmic devices with low contact resistance or negligible SBH in Table S2. They suggested various process and contact methods to overcome Schottky contact behaviors and limited performances. ,,− Compared to previous reports, we find that this work demonstrates a very small SBH formed at the metal interface, which facilitates barrier-free carrier transport.…”

Investigation on Contact Properties of 2D van der Waals Semimetallic 1T-TiS2/MoS2 Heterojunctions

“…Given that the SBH plays a crucial role in the current flow of the device in the off-state, this can be attributed to the enhanced carrier transport resulting from the low SBH compared to the MoS 2 FET with the Ti/Au contact. Furthermore, the increased carrier density of MoS 2 beneath TiS 2 , as a result of the gap-state saturation, can contribute to enhance carrier transport efficiency. − Based on device characterization results, we found 10 nm to be the optimal thickness of the TiS 2 contact.…”