Low-Resistance 2D/2D Ohmic Contacts: A Universal Approach to High-Performance WSe₂, MoS₂, and MoSe₂ Transistors

Abstract

We report a new strategy for fabricating 2D/2D low-resistance ohmic contacts for a variety of transition metal dichalcogenides (TMDs) using van der Waals assembly of substitutionally doped TMDs as drain/source contacts and TMDs with no intentional doping as channel materials. We demonstrate that few-layer WSe 2 field-effect transistors (FETs) with 2D/2D contacts exhibit low contact resistances of ~ 0.3 kΩ µm, high on/off ratios up to > 10 9 , and high drive currents exceeding 320 µA µm -1 . These favorable characteristics are combined with a two-terminal field-effect hole mobility μ FE ≈ 2×10 2 cm 2 V -1 s -1 at room temperature, which increases to >2×10 3 cm 2 V -1 s -1 at cryogenic temperatures. We observe a similar performance also in MoS 2 and MoSe 2 FETs with 2D/2D drain and source contacts. The 2D/2D low-resistance ohmic contacts presented here represent a new device paradigm that overcomes a significant bottleneck in the performance of TMDs and a wide variety of other 2D materials as the channel materials in post-silicon electronics.

Metallic Vanadium Disulfide Nanosheets as a Platform Material for Multifunctional Electrode Applications

“…The greatly improved device performance is attributed to the highquality vdW interface which is free of Fermi level pinning effects 45 , thus enabling efficient charge injection from the VS2 electrode into the MoS2 channel (more discussion can be found in Supplementary Figure S12). The VS2 nanosheets have also manifested impressive performance as supercapacitor electrodes for energy-related applications.…”

WSe 2 -contact metal interface chemistry and band alignment under high vacuum and ultra high vacuum deposition conditions

“…500 cm 2 V −1 s −1 ) in WSe 2 based devices if contact resistance effects are overlooked [9][10][11]. Although WSe 2 , among other TMDs, shows tremendous potential for the realization of a new class of low power devices, contact resistance (0.2 kΩ μm) [12] in TMD-based devices is an order of magnitude greater than what has been achieved in Si-based devices (0.01 kΩ μm) to date [8,13,14].…”

“…Analogous doping schemes involving surface charge transfer [15,16] or substitution [17] have been developed for TMDs, although doping effects degrade in air for many of these strategies. Alternative methods have been employed recently in TMD-based devices for reduced contact resistance and WSe 2 -contact metal interface chemistry and band alignment under high vacuum and ultra high vacuum deposition conditions 2 C M Smyth et al include but are not limited to a WO x hole injection layer [18], metallic edge contacts [12,19], vacuum annealing [20], and metallic 2D top contacts [11,21]. Contact resistances from 0.2 to 2 kΩ μm have been achieved in WSe 2 -based FETs employing the strategies listed above.…”

Broad Detection Range Rhenium Diselenide Photodetector Enhanced by (3‐Aminopropyl)Triethoxysilane and Triphenylphosphine Treatment

“…[ 39 ] After applying PPh 3 doping, we observed a slight red-shift in the E g -like and A g -like Raman peaks (dotted red line) and the peak shift values are plotted in Figure 1 b (including error bars). [ 13 ] Indeed, these materials form various metal-TMD junctions, such as Ohmic or Schottky [ 14,15 ] junctions, and also present different energy band gaps [ 16 ] depending on the type of TMDs, thereby providing versatile electrical and optical characteristics in TMD-based devices. For reference, previous Raman studies on n-doped TMDs also reported red-shifting phenomenon in Raman peaks.…”