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| Main Authors: | , , , , , , , , , , , , , , , , , , , , , , , , , , , , |
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| Format: | Preprint |
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2025
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2507.16137 |
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| _version_ | 1866915404123734016 |
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| author | Yukawa, Ryu Mizuseki, Hiroshi Putro, Suryo Santoso Lee, Yé-Jin L. Masutake, Yuuki Telengut, Hinako Li, Boxuan Yamamoto, Hajime Abukawa, Tadashi Yoshida, Junya Kochurikhin, Vladimir V. Tomida, Taketoshi Kitahara, Masanori Horiai, Takahiko Yoshikawa, Akira Sarukura, Nobuhiko Chikumoto, Noriko Shimizu, Toshihiko Cadatal-Raduban, Marilou Kawazoe, Yoshiyuki Kohno, Ryuhei Kumigashira, Hiroshi Nakamura, Takuto Kanda, Tatsuhiko Yasui, Akira Kitamura, Miho Iwasawa, Hideaki Horiba, Koji Ozawa, Kenichi |
| author_facet | Yukawa, Ryu Mizuseki, Hiroshi Putro, Suryo Santoso Lee, Yé-Jin L. Masutake, Yuuki Telengut, Hinako Li, Boxuan Yamamoto, Hajime Abukawa, Tadashi Yoshida, Junya Kochurikhin, Vladimir V. Tomida, Taketoshi Kitahara, Masanori Horiai, Takahiko Yoshikawa, Akira Sarukura, Nobuhiko Chikumoto, Noriko Shimizu, Toshihiko Cadatal-Raduban, Marilou Kawazoe, Yoshiyuki Kohno, Ryuhei Kumigashira, Hiroshi Nakamura, Takuto Kanda, Tatsuhiko Yasui, Akira Kitamura, Miho Iwasawa, Hideaki Horiba, Koji Ozawa, Kenichi |
| contents | Ultra-wide bandgap (UWBG) semiconductors promise to revolutionize power electronics, yet a fundamental understanding of their interfacial electronic structure has been hindered by the absence of direct experimental observation. Here, we report the first momentum-resolved observation of two-dimensional electron systems on a UWBG material, enabled by angle resolved photoemission spectroscopy (ARPES) on high-purity $β$-Ga$_2$O$_3$ single crystals. Alkaline-metal-induced electron doping forms an isotropic circular Fermi surface, achieving a sheet carrier density of up to $1.0\times10^{14}$ $\mathrm{cm}^{-2}$. Self-consistent Poisson-Schrödinger calculations show that the electrons are confined within 1.2 nm of the surface and reveal an internal electric field of $18$ MV cm$^{-1}$. Crucially, our measurements reveal a pronounced renormalization of the electronic band structure: a series of carrier-density-dependent ARPES measurements shows that as the carrier density increases from $2\times10^{13}$ to $1.0\times10^{14}$ $\mathrm{cm}^{-2}$, the effective mass anomalously increases, nearly doubling to a final value of 0.48 $\textit{m}_{\mathrm{e}}$. This trend is notably opposite to that reported for other oxide semiconductors, pointing towards a unique renormalization mechanism in $β$-Ga$_2$O$_3$. Our findings establish the interfacial electronic structure of $β$-Ga$_2$O$_3$ and demonstrate that UWBG materials provide fertile ground for exploring carrier-density-driven electronic phenomena, opening new avenues for future quantum and power devices. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2507_16137 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Unveiling two-dimensional electron systems on ultra-wide bandgap semiconductor $\mathrmβ$-Ga$_2$O$_3$ Yukawa, Ryu Mizuseki, Hiroshi Putro, Suryo Santoso Lee, Yé-Jin L. Masutake, Yuuki Telengut, Hinako Li, Boxuan Yamamoto, Hajime Abukawa, Tadashi Yoshida, Junya Kochurikhin, Vladimir V. Tomida, Taketoshi Kitahara, Masanori Horiai, Takahiko Yoshikawa, Akira Sarukura, Nobuhiko Chikumoto, Noriko Shimizu, Toshihiko Cadatal-Raduban, Marilou Kawazoe, Yoshiyuki Kohno, Ryuhei Kumigashira, Hiroshi Nakamura, Takuto Kanda, Tatsuhiko Yasui, Akira Kitamura, Miho Iwasawa, Hideaki Horiba, Koji Ozawa, Kenichi Materials Science Ultra-wide bandgap (UWBG) semiconductors promise to revolutionize power electronics, yet a fundamental understanding of their interfacial electronic structure has been hindered by the absence of direct experimental observation. Here, we report the first momentum-resolved observation of two-dimensional electron systems on a UWBG material, enabled by angle resolved photoemission spectroscopy (ARPES) on high-purity $β$-Ga$_2$O$_3$ single crystals. Alkaline-metal-induced electron doping forms an isotropic circular Fermi surface, achieving a sheet carrier density of up to $1.0\times10^{14}$ $\mathrm{cm}^{-2}$. Self-consistent Poisson-Schrödinger calculations show that the electrons are confined within 1.2 nm of the surface and reveal an internal electric field of $18$ MV cm$^{-1}$. Crucially, our measurements reveal a pronounced renormalization of the electronic band structure: a series of carrier-density-dependent ARPES measurements shows that as the carrier density increases from $2\times10^{13}$ to $1.0\times10^{14}$ $\mathrm{cm}^{-2}$, the effective mass anomalously increases, nearly doubling to a final value of 0.48 $\textit{m}_{\mathrm{e}}$. This trend is notably opposite to that reported for other oxide semiconductors, pointing towards a unique renormalization mechanism in $β$-Ga$_2$O$_3$. Our findings establish the interfacial electronic structure of $β$-Ga$_2$O$_3$ and demonstrate that UWBG materials provide fertile ground for exploring carrier-density-driven electronic phenomena, opening new avenues for future quantum and power devices. |
| title | Unveiling two-dimensional electron systems on ultra-wide bandgap semiconductor $\mathrmβ$-Ga$_2$O$_3$ |
| topic | Materials Science |
| url | https://arxiv.org/abs/2507.16137 |