Graphite-metal composite electrodes with a tunable work function for use in optoelectronic devices

Kesavan, AV and Khot, AC and Dongale, TD and Son, KR and Ramamurthy, PC and Kim, TG (2022) Graphite-metal composite electrodes with a tunable work function for use in optoelectronic devices. In: Journal of Materials Chemistry C .

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Abstract

In electronic devices, the work function (WF) of the electrodes must be tailored to achieve a well-aligned Ohmic or Schottky contact. Low- and high-WF electrodes are typically used to ensure effective injection/extraction of electrons and holes. In this study, composite graphite-aluminum (G : Al) and graphite-nickel (G : Ni) electrodes were deposited on a glass substrate using electron beam evaporation, and ambient pressure photoemission spectroscopy was conducted to evaluate the WF of the fabricated electrodes. The WF of the G : Al electrode was successfully tuned from 4.24 ± 0.047 eV to 5.10 ± 0.031 eV (a range of ∼0.9 eV) by increasing the graphite content. Similarly, the WF of the G : Ni composite electrode was tuned from 4.67 ± 0.041 eV to 5.11 ± 0.031 eV (a range of ∼0.4 eV). The shift in the WF in the composite graphite-metal electrodes could be explained by the formation of metal-metal (or semiconductor) junctions. The optical reflectance, sheet resistance, and morphology were also able to be tuned. The sheet resistance of the G : Al and G : Ni electrodes varied from 2.28 ± 0.03 Ω sq−1 to 80.05 ± 9.1 Ω sq−1 and from 4.92 ± 0.04 Ω sq−1 to 166.30 ± 4.1 Ω sq−1, respectively, while the total tunable reflectance was 53.77% and 45.70%, respectively. This research demonstrates a novel exploratory technique for tailoring the WF of hybrid graphite materials.

Item Type:	Journal Article
Publication:	Journal of Materials Chemistry C
Publisher:	Royal Society of Chemistry
Additional Information:	The copyright for this article belongs to the Royal Society of Chemistry.
Keywords:	Glass substrates; Graphite electrodes; Morphology; Optoelectronic devices; Work function, Composites electrodes; Electronics devices; Electrons and holes; Glass substrates; Graphite metal composites; High work function; Nickel electrode; Optoelectronics devices; Schottky contacts; Tunables, Metals
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	07 Nov 2022 10:04
Last Modified:	07 Nov 2022 10:04
URI:	https://eprints.iisc.ac.in/id/eprint/77843

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