Extended Data Fig. 9: Performance projection of Bi–monolayer TMD technology.
From: Ultralow contact resistance between semimetal and monolayer semiconductors
a, Fraction of channel resistance (RCH, green line) and total contact resistance (2RC, blue line) with respect to the total device resistance (RTOT = RCH + 2RC) in Bi–MoS2 FETs as a function of the channel length (LCH) at room temperature based on the device and material parameters extracted from Fig. 2c. The dashed lines show the quantum limit, representing the minimum RC that can be achieved in a transistor. The quantum limit RC is πh/(4q2kF) ≈ 0.036(n2D)−0.5 kΩ μm, which is determined by the quantum resistance (h/2q2 ≈ 12.9 kΩ) and the number of conducting modes per channel width (kF/π), which is related to the 2D sheet carrier density (n2D, in units of 1013 cm–2)2. b, Projection of 2RC as a function of the contact length (LC) in monolayer TMD transistors based on the transmission line model with various metal contacts at room temperature. The vertical dashed line represents the current transfer length (LT) for each metal contact. The results are calculated based on the data extracted from previously reported TLM results13,47. As can be seen, RC increases as LC becomes comparable to LT, owing to the current-crowding effect (equation (4))18. Note that In, hexagonal boron nitride (hBN)/Co, Ni and high-vacuum Au contacts to monolayer MoS2 exhibit similar values of RC (~3–6 kΩ μm) and ρC (~10−6–10−5 Ω cm2)13,14,18,50. c, Required minimum VDS for Bi-contacted monolayer TMD transistors to work in the velocity saturation regime using our best RC of 123 Ω μm and a theoretical FC of 1.15 × 105 V cm−1. The VDD required by IRDS is also plotted. d, The required VDS to bias monolayer MoS2 transistors in the velocity-saturation regime for different contact technologies.
