Figure 3
From: Vertical WS2/SnS2 van der Waals Heterostructure for Tunneling Transistors
Optimization of p-type contact for WS2. (a) Measured transfer characteristics of p-type WS2 SB-FETs using Pd and Pt contacts (VBG,T = VBG − Vonset(Pt), Vonset(Pt): the onset voltage at which hole current begins to increase in the Pt-contacted SB-FET). Similar currents are observed in these two devices. (b) Dependence of on-state current density on WS2 thickness in WS2 SB-FETs. The on-state hole current increases with the number of WS2 layers. (c) Measured transfer characteristics of SB-FET with 23 nm-thick WS2. Large hole current in the on-state indicates the low resistance p-type contact. (d) AFM height profile of the 32-layer WS2 sheet. Inset is the corresponding AFM image of fabricated devices.
