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arXiv · 2010.15883

Two-dimensional hole gas in organic semiconductors

Naotaka Kasuya·Junto Tsurumi·Toshihiro Okamoto·Shun Watanabe·Jun Takeya
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Abstract

A highly conductive metallic gas that is quantum mechanically confined at a solid-state interface is an ideal platform to explore nontrivial electronic states that are otherwise inaccessible in bulk materials. Although two-dimensional electron gas (2DEG) has been realized in conventional semiconductor interfaces, examples of two-dimensional hole gas (2DHG), which is the counter analogue of 2DEG, are still limited. Here, we report the observation of a 2DHG in solution-processed organic semiconductors in conjunction with an electric double-layer using ionic liquids. A molecularly flat single crystal of high mobility organic semiconductors serves as a defect-free interface that facilitates two-dimensional confinement of high-density holes. Remarkably low sheet resistance of 6 k$\Omega$ and high hole gas density of 10$^{14}$ cm$^{-2}$ result in a metal-insulator transition at ambient pressure. The measured degenerated holes in the organic semiconductors provide a broad opportunity to tailor low-dimensional electronic states using molecularly engineered heterointerfaces.

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Naotaka Kasuya, Junto Tsurumi, Toshihiro Okamoto, Shun Watanabe, Jun Takeya. 2020-10-29. Two-dimensional hole gas in organic semiconductors. https://doi.org/10.1038/s41563-021-01074-4

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