Lowering Contact Resistances of Two-Dimensional Semiconductors by Memristive Forming

Abstract

Two-dimensional semiconductors have great potential for beyond-silicon electronics. However, because of the lack of controllable doping methods, Fermi level pinning, and van der Waals (vdW) gaps at the metal–semiconductor interfaces, these devices exhibit high electrical contact resistances, restricting their practical applications. Here, we report a general contact-resistance-lowering strategy by constructing vertical metal–semiconductor–metal memristor structures at the contact regions and setting them into a nonvolatile low-resistance state through a memristive forming process. Through this, we reduce the contact resistances of MoS2 field-effect transistors (FETs) by at least one order of magnitude and improve the on-state current densities of MoTe2 FETs by about two orders of magnitude. We also demonstrate that this strategy is applicable to other two-dimensional semiconductors, including MoSe2, WS2, and WSe2, and a variety of contact metals, including Au, Cu, Ni, and Pd. The good stability and universality indicate the great potential for technological applications.

Improving Contacts and Electrical Performances of Nanofilms of MoS2 Transistors through Ultrastrong vdW Integration with Dirac Semimetal PtTe2

“…Interlayer coupling plays a fundamental role not only in the electronic properties of vdW heterostructures but also in the vdW gap. , Recently, Z. Wu et al demonstrated that nonvolatile memristive forming can eliminate the vdW gap between 2D channels and contact electrodes, thus reducing the contact resistance by at least 1 order of magnitude . Besides the type-I Dirac semimetal represented by graphene, the layered PtTe 2 as a type-II Dirac semimetal is an emerging semimetallic material and has wide-ranging potential applications in mid-infrared and even terahertz photodetection. , It has been experimentally verified that PtTe 2 as electrodes can reduce contact resistance through an edge-to-edge connection between PtTe 2 and 2D semiconductors. , Those edge contacts based on a lateral heterostructure synthesized by the CVD route are incompatible with current semiconductor manufacturing processes .…”

“…28,29 Recently, Z. Wu et al demonstrated that nonvolatile memristive forming can eliminate the vdW gap between 2D channels and contact electrodes, thus reducing the contact resistance by at least 1 order of magnitude. 30 Besides the type-I Dirac semimetal represented by graphene, the layered PtTe 2 as a type-II Dirac semimetal is an emerging semimetallic material and has wide-ranging potential applications in midinfrared and even terahertz photodetection. 31,32 It has been experimentally verified that PtTe 2 as electrodes can reduce contact resistance through an edge-to-edge connection between PtTe 2 and 2D semiconductors.…”