Record-high drain current in p-type 2D transistors with high-k dielectric and accumulation-type contacts

2D van der Waals materials are promising candidates for ultimate device miniaturization. However, high-performance 2D p-type transistors are an important missing piece in potential 2D-based CMOS technology. Here we demonstrate that with a novel high-mobility narrow-bandgap p-type material tellurium, high-performance FETs can be realized for low-power ultra-fast electronic applications. Unprecedented high on-state current beyond 1 A/mm is achieved with advanced dielectric and contact engineering. The large EOT/breakdown field of the ALD-grown high-k dielectric allows a stronger displacement field which induces higher carrier density. Meanwhile we revisited the fundamental difference of metal-to-semiconductor interface between van der Waals materials and 3D bulk materials. The Fermi pinning effect, which governs the contact behavior in most traditional semiconductors, was significantly reduced in our device and for the first time accumulation-type Ohmic contacts are achieved on p-type 2D semiconductor tellurium.