Improving Electric Contacts to Two-Dimensional Semiconductors

Abstract

Electrical contact resistance to two-dimensional (2D) semiconductors such as monolayer MoS_{2} is a key bottleneck in scaling the 2D field effect transistors (FETs). The 2D semiconductor in contact with three-dimensional metal creates unique current crowding that leads to increased contact resistance. We developed a model to separate the contribution of the current crowding from the intrinsic contact resistivity. We show that current crowding can be alleviated by doping and contact patterning. Using Landauer-Büttiker formalism, we show that van der Waals (vdW) gap at the interface will ultimately limit the electrical contact resistance. We compare our models with experimental data for doped and undoped MoS_{2} FETs. Even with heavy charge-transfer doping of > 2x10^{13} cm^{-2}, we show that the state-of-the-art contact resistance is 100 times larger than the ballistic limit. Our study highlights the need to develop efficient interface to achieve contact resistance of < 10 Ω.μm, which will be ideal for extremely scaled devices.

References in corpus (8)

• Improved Contacts to MoS2 Transistors by Ultra-High Vacuum Metal Deposition
• Atomically-thin Ohmic Edge Contacts Between Two-dimensional Materials
• Perspectives for Spintronics in 2D Materials
• On Landauer vs. Boltzmann and Full Band vs. Effective Mass Evaluation of Thermoelectric Transport Coefficients
• S2DS: Physics-Based Compact Model for Circuit Simulation of Two-Dimensional Semiconductor Devices Including Non-Idealities
• Nature of carrier injection in metal/2D semiconductor interface and its implications to the limits of contact resistance
• Absence of a Band Gap at Interface of a Metal and Highly Doped Monolayer $Mo{S}_2$
• Semi-analytical model of the contact resistance in two-dimensional semiconductors