Fig. 1

Fabrication and characterisation of asymmetric electrode nanogap Schottky diodes. a, Process steps used to fabricate the ZnO Schottky diodes based on Al and Au coplanar nanogap electrodes: (1) Deposition of the ODPA SAM on top of a patterned Al electrode, (2) blanket thermal evaporation of Au across the entire substrate, (3) nanogap development by removing the Au layer from areas where it overlaps with the Al/ODPA electrodes via dipping in hot NMP, (4) SAM removal by brief exposure to argon plasma, (5) the empty Al-Au nanogap electrodes, (6) ZnO deposition onto the nanogap electrodes via sequential spin coating and thermal annealing. b, SEM top-view image of a representative Al-Au nanogap. c, High-resolution TEM cross-sectional view of the Al-Au nanogap revealing a ≈15 nm inter-electrode distance. d, Photography of a 4-inch glass wafer containing NGE-based ZnO Schottky diodes and circuits. The inset shows a zoomed image of a discrete interdigitated NGE-based ZnO diode.