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

Wafer-scale fabrication of PtSe ₂ MOSFETs was demonstrated by photolithography on Pt films directly selenized at 400 °C. Taking advantage of the unique property of PtSe ₂ 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 Ω · 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 μA/μm for 4-, 8-, and 12-nm-thick PtSe ₂ , respectively. The corresponding peak transconductances were 0.20 ± 0.1, 0.60 ± 0.05, and 1.4 ± 0.1 μS/μm. The forward-current cutoff frequency of 12-nm-thick PtSe ₂ MOSFETs was 42 ± 5 MHz, whereas the corresponding frequency of maximum oscillation was 180 ± 30 MHz. These results confirmed the application potential of PtSe ₂ for future-generation thin-film transistors.