Fig. 4: Defect band alignment in Al2O3.
From: Improving stability in two-dimensional transistors with amorphous gate oxides by Fermi-level tuning
a, Band diagram illustrates the alignment of the Al2O3 defect band to Type 1 and Type 2 graphene. The location of defect bands as extracted from experiments is shown: (1) (ref. 28), (2) (ref. 54), (3) (ref. 55), (4) (ref. 56) and (5) (ref. 20). Also, the alignment of the defect band caused by oxygen vacancies and Al interstitials in amorphous Al2O3 is shown according to DFT calculations (6) (ref. 57). b, Active region probed by measurements in the [–5, 5 V] and [–10, 10 V] range is shown for two defect band alignments for Type 1 GFETs. c, Schematic of the band diagrams showing the charging and discharging of defects in Al2O3 for Type 1 graphene with a work function of EW = 4.6 eV—a value that can be qualitatively reached also with VBG ≥ +20 V. d, Band diagrams for Type 2 graphene with EW = 4.8 eV are shown, an effective doping level qualitatively accessible with VBG ≤ –20 V.
