Contact Gating in Dual-Gated WS2 MOSFETs With Semi-Metallic Bi Contacts

The effect of contact gating is studied in high-performance, dual-gated, single-layer (1L) WS ₂ MOSFETs with semi-metallic Bi contacts. Using a dual-gate geometry, we study the contribution of contact gating in lowering contact resistance, ${R}_{C}$ , by changing the top-gate and bottom-gate voltages independently. The ${R}_{C}$ of the bottom-gated biasing configuration shows ~20x lower contact resistance than the top-gated biasing configuration. ${R}_{C}$ is shown to be strongly affected by the bottom gate voltage, even at fixed channel carrier concentration, and this dependence is shown to be related to modulation of the transfer length by the bottom gate. The results show that despite the importance of semi-metallic materials in improving contact resistance, contact gating is still necessary to achieve ultra-low contact resistance.