Maskless Device Fabrication and Laser-Induced Doping in MoS2 Field Effect Transistors Using a Thermally Activated Cyclic Polyphthalaldehyde Resist

We present a novel maskless device fabrication technique for rapid prototyping of two-dimensional (2D)-based electronic materials. The technique is based on a thermally activated and self-developed cyclic polyphthalaldehyde (c-PPA) resist using a commercial Raman system and 532 nm laser illumination. Following the successful customization of electrodes to form field effect transistors based on MoS2 monolayers, the laser-induced electronic doping of areas beneath the metal contacts that were exposed during lithography was investigated using both surface potential mapping and device characterization. An effective change in the doping level was introduced depending on the laser intensity, i.e., low laser powers resulted in p-doping, while high laser powers resulted in n-doping. Fabricated devices present a low contact resistance down to 10 k Omega.mu m at a back-gate voltage of V-G = 80 V, which is attributed to the laser-induced n-type doping at the metal contact regions.

Automated summary

A novel maskless device fabrication technique utilizing a thermally activated cyclic polyphthalaldehyde resist was presented for rapid prototyping of 2D-based electronic materials. Laser-induced electronic doping was investigated for areas beneath metal contacts, resulting in effective changes in doping levels depending on laser intensity. The fabricated devices showed low contact resistance attributed to laser-induced n-type doping at metal contact regions.