Diffused Beam Energy to Dope van der Waals Electronics and Boost Their Contact Barrier Lowering.

Contact engineering of two-dimensional semiconductors is a central issue for performance improvement of micro-/nanodevices based on these materials. Unfortunately, the various methods proposed to improve the Schottky barrier height normally require the use of high temperatures, chemical dopants, or complex processes. This work demonstrates that diffused electron beam energy (DEBE) treatment can simultaneously reduce the Schottky barrier height and enable the direct writing of electrical circuitry on van der Waals semiconductors. The electron beam energy projected into the region outside the electrode diffuses into the main channel, producing selective-area n-type doping in a layered MoTe 2 (or MoS 2 ) field-effect transistor. As a result, the Schottky barrier height at the interface between the electrode and the DEBE-treated MoTe 2 channel is as low as 12 meV. Additionally, because selective-area doping is possible, DEBE can allow the formation of both n- and p-type doped channels within the same atomic plane, which enables the creation of a nonvolatile and homogeneous MoTe 2 p-n rectifier with an ideality factor of 1.1 and a rectification ratio of 1.3 × 10 3 . These results indicate that the DEBE method is a simple, efficient, mask-free, and chemical dopant-free approach to selective-area doping for the development of van der Waals electronics with excellent device performances.