High-Performance Flexible Schottky Diodes Based on Sputtered InGaZnO

Abstract

High-performance flexible InGaZnO-based Schottky diodes are fabricated on polyethylene terephthalate (PET) and polyimide (PI) substrates at room temperature without any thermal treatment. The diode performance improves significantly by either oxygen plasma or UV-ozone treatment on Pd anode. X-ray photoelectron spectroscopy indicates that both treatments lead to Pd surface oxidation. The oxygen plasma treatment results in more complete oxidation, and thus ensures better oxygen stoichiometry at the Schottky interface and a higher anode work function. This leads to high performance with on/off ratios of 7.3 × 10 ⁶ and 2.6 × 10 ⁴ , barrier heights of 0.79 and 0.76 eV, and ideality factors of 1.22 and 1.19 on PET and PI, respectively. Interestingly, these flexible diodes show improved performance after storing in ambient air for two years, and fittings on the reverse currents indicate an improved barrier uniformity. The flexible diode on PET after a two-year storage achieves a high on/off ratio of 2 107, a large barrier height of 0.80 eV, a close to unity ideality factor of 1.09, a high breakdown voltage of -7.5 V, and robust performance upon outward or inward bending, which is, to the best of our knowledge, the highest performance in reported flexible diodes to date.