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arXiv · 2111.10576

Contact conductance governs metallicity in conducting metal oxide nanocrystal films

Corey M. Staller·Stephen L. Gibbs·Xing Yee Gan·Jay T. Bender·Karalee Jarvis·Gary K. Ong·Delia J. Milliron
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Abstract

In bulk semiconductor materials, the insulator-metal transition (IMT) is governed by the concentration of conduction electrons. Meanwhile, even when fabricated from metallic building blocks, nanocrystal films are often insulating with inter-nanocrystal contacts acting as electron transport bottlenecks. Using a library of transparent conducting tin-doped indium oxide nanocrystal films with varied electron concentration, size, and contact area, we test candidate criteria for the IMT and establish a phase diagram for electron transport behavior. From variable temperature conductivity measurements, we learn that both the IMT and a subsequent crossover to conventional metallic behavior near room temperature are governed by the conductance of the inter-nanocrystal contacts. To cross the IMT, inter-nanocrystal coupling must be sufficient to overcome the charging energy of a nanocrystal, while conventional metallic behavior requires contact conductance to reach the conductance of a nanocrystal. This understanding can enable the design and fabrication of metallic conducting materials from nanocrystal building blocks.

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Corey M. Staller, Stephen L. Gibbs, Xing Yee Gan, Jay T. Bender, Karalee Jarvis, Gary K. Ong, Delia J. Milliron. 2021-11-20. Contact conductance governs metallicity in conducting metal oxide nanocrystal films. https://doi.org/10.1021/acs.nanolett.2c01852

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