High-performance few-layer-MoS2 field-effect-transistor with record low contact-resistance

Recently, Molybdenum Disulphide (MoS
₂
) has emerged as a promising candidate for low-power digital applications. Compared to monolayer (1L) MoS
₂
, few-layer MoS
₂
(FL-MoS
₂
) is attractive due to its higher density of states (DOS). However, a comprehensive study of FL-MoS
₂
field-effect-transistor (FET) is lacking. In this paper, we report a high-performance FL-MoS
₂
FET with record low contact resistance (~0.8 KΩ.μm) that is close to the value for metal-silicon contacts in CMOS technology. A correlation of device performance and the number of MoS
₂
layers is established to guide the design of high-performance FL-MoS
₂
FET. Moreover, it is found that edge contacts (metal contact to each edge of MoS
₂
layers) play a key role in the efficient injection of electrons from metal to MoS
₂
. This is confirmed by experiments as well as density functional theory (DFT) calculations. Moreover, a top gated FL-MoS
₂
(5 nm) FET is also demonstrated with a robust current saturation and high drive current (24 μA/μm) even without source/drain doping.