Chalcogen Assisted Enhanced Atomic Orbital Interaction at TMDs - Metal Interface & Chalcogen Passivation of TMD Channel For Overall Performance Boost of 2D TMD FETs

Abstract

Metal-semiconductor interface is a bottleneck for efficient transport of charge carriers through Transition Metal Dichalcogenide (TMD) based field-effect transistors (FETs). Injection of charge carriers across such interfaces is mostly limited by Schottky barrier at the contacts which must be reduced to achieve highly efficient contacts for carrier injection into the channel. Here we introduce a universal approach involving dry chemistry to enhance atomic orbital interaction between various TMDs (MoS2, WS2, MoSe2 and WSe2) & metal contacts has been experimentally demonstrated. Quantum chemistry between TMDs, Chalcogens and metals has been explored using detailed atomistic (DFT & NEGF) simulations, which is then verified using Raman, PL and XPS investigations. Atomistic investigations revealed lower contact resistance due to enhanced orbital interaction and unique physics of charge sharing between constituent atoms in TMDs with introduced Chalcogen atoms which is subsequently validated through experiments. Besides contact engineering, which lowered contact resistance by 72, 86, 1.8, 13 times in MoS2, WS2, MoSe2 and WSe2 respectively, a novel approach to cure / passivate dangling bonds present at the 2D TMD channel surface has been demonstrated. While the contact engineering improved the ON-state performance (ION, gm, mobility and RON) of 2D TMD FETs by orders of magnitude, Chalcogen based channel passivation was found to improve gate control (IOFF, SS, & VTH) significantly. This resulted in an overall performance boost. The engineered TMD FETs were shown to have performance on par with best reported till date.

References in corpus (6)

• Tunable Photoluminescence of Monolayer MoS2 via Chemical Doping
• Symmetry-dependent phonon renormalization in monolayer MoS2 transistor
• Electrical Transport Properties of Single-Layer WS2
• Chloride Molecular Doping Technique on 2D Materials: WS2 and MoS2
• Field-effect transistors and intrinsic mobility in ultra-thin MoSe2 layers
• Molecular Doping of Multilayer MoS2 Field-effect Transistors: Reduction in Sheet and Contact Resistances

Cited by in corpus (1)

• Contact resistance and interfacial engineering: Advances in high-performance 2D-TMD based devices