Wafer-scale Fabrication and Characterization of Recessed-channel PtSe2 MOSFETs with Low Contact Resistance and Improved Gate Control

For the first time, wafer-scale fabrication of PtSe2 MOSFETs was demonstrated by photolithography. The on PtSe2 is grown by thermally assisted conversion (TAC) of Pt films under Se vapor at 400 °C. Taking advantage of the unique property of PtSe2 to transition from semiconductor to semimetal as its thickness increases beyond a few monolayers, channel recess was adapted for improving gate control while keeping the contact resistance as low as 0.008 Ω∙cm. The wafer-scale fabrication resulted in uniform device characteristics so that average vs. best results were reported, as well as RF vs. DC characteristics. For example, the drain current at VGS = −10, VDS = −1 V were 25 ± 5, 57 ± 8, and 618 ± 17 μA/μm for 4-, 8-, and 12-nm-thick PtSe2, respectively. The corresponding peak transconductances were 0.20 ± 0.1, 0.60 ± 0.05, and 1.4 ± 0.1 μS/μm. The forward-current cut-off frequency of 12-nm-thick PtSe2 MOSFETs was 42 ± 5 MHz, whereas the corresponding frequency of maximum oscillation was 180 ± 30 MHz. These results confirmed the application potential of PtSe2 for future generation thin-film transistors