Wafer-Scale Fabrication of Recessed-Channel PtSe2 MOSFETs With Low Contact Resistance and Improved Gate Control

Wafer scale fabrication of PtSe2 MOSFETs was demonstrated by photolithography on Pt films directly selenized at 400 degrees C. Taking advantage of the unique property of PtSe2 to transition from a semiconductor to a semimetal as its thickness increases beyond a few monolayers, channel recess was adapted for improving gate control while keeping the contact resistance below 0.01 Omega . cm. The wafer-scale fabrication resulted in uniform device characteristics so that average instead of best results was reported. For example, the drain currents at V-GS = -10 V, V-DS = -1 V were 25 +/- 5, 57 +/- 8, and 618 +/- 17 mu A/mu m 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 mu S/mu m. The forward-current cutoff 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.