First synthesized WS2 nanotube and nanoribbon field effect transistors grown by chemical vapor transport

While planar two-dimensional field effect transistors (FETs) are being widely explored [1], there are only a few reports of MoS
₂
[2-4] and WS
₂
[5-8] nanotube (NT) and nanoribbon (NR) FETs. A benefit of these crystalline forms is the absence of edges associated with traps, and the potential for ideal subthreshold swing with wrapped gates. Density functional theory predicts that the bandgap of MoS
₂
nanotubes remains direct and decreases with diameter [9] due to strain. This makes nanotubes appealing for tunnel FETs at the scaling limit because the decrease in bandgap should provide an increase in current. Here we report the first WS
₂
NT and NR FETs synthesized by chemical vapor transport (CVT) [10]. Prior reports on WS
₂
[5-8] are based on sulphurization of W and WO nanowhiskers.