Extended Data Fig. 2: TCAD estimate of the stability improvement for insulators with narrow defect bands.
From: Improving stability in two-dimensional transistors with amorphous gate oxides by Fermi-level tuning
For a defect band which is only 0.07eV wide, the hysteresis can be considerably reduced with Fermi level tuning. Here, a model system of MoS2 and SiO2 with a hypothetical, narrow defect band is used. (a) The hysteresis width ΔVH is extracted at the threshold voltage, defined as EF being located at 50 meV below the conduction band edge, see the bending of the band edges at the top. This corresponds to a constant current criterion of Icrit = 4.8 × 10−5μA/μm. (b) The hysteresis width ΔVH is shown as a function of the distance of the oxide trap level ET to the MoS2 conduction band edge EC. If EC is moved 82 meV away from the trap band, the hysteresis width will improve by one order of magnitude. (c) At two different locations of EC, namely at ET − EC = 0.168 eV in dark blue and 0.25 eV in light blue corresponding to the colors of the dotted lines in (b), the band diagrams of the MoS2/SiO2 system are shown, demonstrating how fewer oxide traps change their charge state if the conduction band edge is shifted down.
