Scaling-up Atomically Thin Coplanar Semiconductor–Metal Circuitry via Phase Engineered Chemical Assembly

Abstract

Two-dimensional (2D) layered semiconductors, with their ultimate atomic thickness, have shown promise to scale down transistors for modern integrated circuitry. However, the electrical contacts that connect these materials with external bulky metals are usually unsatisfactory, which limits the transistor performance. Recently, contacting 2D semiconductors using coplanar 2D conductors has shown promise in reducing the problematic high resistance contacts. However, many of these methods are not ideal for scaled production.Here, we report on the large-scale, spatially controlled chemical assembly of the integrated 2H-MoTe 2 field-effect transistors (FETs) with coplanar metallic 1T′-MoTe 2 contacts via phase engineered approaches. We demonstrate that the heterophase FETs exhibit ohmic contact behavior with low contact resistance, resulting from the coplanar seamless contact between 2H and 1T′ MoTe 2 confirmed by transmission electron microscopy characterizations. The average mobility of the heterophase FETs was measured to be as high as 23 cm 2 V −1 s −1 (comparable with those of exfoliated single crystals), due to the large 2H MoTe 2 single-crystalline domain (486±187 μm). By developing a patterned growth method, we realize the 1T′ MoTe 2 gated heterophase FET array whose components of channel, gate, and contacts are all 2D materials. Finally, we transfer the heterophase device array onto a flexible substrate and demonstrate the near-infrared photoresponse with high photoresponsivity (~1.02 A/W). Our study provides a basis for the large-scale application of phase-engineered coplanar MoTe 2 semiconductors-meter structure in advanced electronics and optoelectronics.

Relaxation and transfer of photoexcited electrons at a coplanar few-layer 1 T′/2H-MoTe2 heterojunction

“…The result confirmed a higher work function of the 1 T′-MoTe 2 than that of the 2H-MoTe 2 . The higher work function of the 1 T′-MoTe 2 is preferable for the ohmic contact of the p-type 2H-MoTe 2 , which is consistent with our previous transport data 38,43 .…”

Direct synthesis of metastable phases of 2D transition metal dichalcogenides

“…155 Interestingly, in MoTe 2 , lateral 1T 0 /2H homojunctions can be obtained via direct CVD synthesis. 160,243,244 The contact barrier height at the lateral 1T 0 /2H interface is reported to be as low as 25-30 meV, 160,243 and in the coplanar 1T 0 /2H contact MoTe 2 FET, the channel mobility reached 16.2 cm 2 V À1 s À1 at room temperature. 243 5.4.…”

Synthesis of 2H‐1T′ WS2‐ReS2 Heterophase Structures with Atomically Sharp Interface via Hydrogen‐Triggered One‐Pot Growth

“…Recently, creating 2D heterostructures between two TMDs with different phase structures, called heterophase junctions, have attracted great research interest, because the modulation of phase structure in 2D heterojunction can endow more degree of freedom for building new interface structures and exploring novel properties and applications. [ 15–20 ] For example, a novel topologically protected helical edge states were discovered at the 1T′‐2H heterophase interface in WSe 2 monolayer. [ 21 ] In addition, Zhang et al found that the 1T′‐2H heterophase interface in MoS 2 monolayer can greatly enhance the catalysis activity for hydrogen evolution.…”