Substitutional Fluorine Doping of Large-Area Molybdenum Disulfide Monolayer Films for Flexible Inverter Device Arrays.

Reliable and controllable doping of transition metal dichalcogenides (TMDCs) is a mandatory requirement for practical large-scale electronic applications. However, most of the literature on the doping methodologies of TMDCs has focused on -type doping and multilayer TMDC rather than a monolayer one enabling large-scale growth. Herein, we report substitutional fluorine doping of a chemical vapor deposition (CVD)-grown molybdenum disulfide (MoS) monolayer film using a delicate SF plasma treatment. Our SF-treated MoS monolayer shows a -type doping effect with fluorine substitution. The doping concentration is controlled by the plasma treatment time (2-4.9 atom %) while maintaining the structural integrity of the MoS monolayer. Such reliable and tunable substitutional doping is attributed to preventing direct ion bombardment to the MoS monolayer by our gentle plasma treatment system. Finally, we fabricated MoS homojunction flexible inverter device arrays based on the pristine and SF-treated MoS monolayer. A clear switching behavior is observed, and the voltage gain is approximately 8 at an applied of 2 V, which is comparable to that of CVD-grown MoS-based inverter devices reported previously. Obtained voltage gain is also stable even after 500 bending cycles at an applied strain of 0.5%.