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Lee H, Campbell N, Lee J, Asel TJ, Paudel TR, Zhou H, Lee JW, Noesges B, Seo J, Park B, Brillson LJ, Oh SH, Tsymbal EY, Rzchowski MS, Eom CB. Direct observation of a two-dimensional hole gas at oxide interfaces. Nat Mater 2018; 17:231-236. [PMID: 29403056 DOI: 10.1038/s41563-017-0002-4] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2017] [Accepted: 11/27/2017] [Indexed: 06/07/2023]
Abstract
The discovery of a two-dimensional electron gas (2DEG) at the LaAlO3/SrTiO3 interface 1 has resulted in the observation of many properties2-5 not present in conventional semiconductor heterostructures, and so become a focal point for device applications6-8. Its counterpart, the two-dimensional hole gas (2DHG), is expected to complement the 2DEG. However, although the 2DEG has been widely observed 9 , the 2DHG has proved elusive. Herein we demonstrate a highly mobile 2DHG in epitaxially grown SrTiO3/LaAlO3/SrTiO3 heterostructures. Using electrical transport measurements and in-line electron holography, we provide direct evidence of a 2DHG that coexists with a 2DEG at complementary heterointerfaces in the same structure. First-principles calculations, coherent Bragg rod analysis and depth-resolved cathodoluminescence spectroscopy consistently support our finding that to eliminate ionic point defects is key to realizing a 2DHG. The coexistence of a 2DEG and a 2DHG in a single oxide heterostructure provides a platform for the exciting physics of confined electron-hole systems and for developing applications.
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Affiliation(s)
- H Lee
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI, USA
| | - N Campbell
- Department of Physics, University of Wisconsin-Madison, Madison, WI, USA
| | - J Lee
- Department of Energy Science, Sungkyunkwan University (SKKU), Suwon, Korea
| | - T J Asel
- Department of Physics, The Ohio State University, Columbus, OH, USA
| | - T R Paudel
- Department of Physics and Astronomy, Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, NE, USA
| | - H Zhou
- X-Ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, IL, USA
| | - J W Lee
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI, USA
| | - B Noesges
- Department of Physics, The Ohio State University, Columbus, OH, USA
| | - J Seo
- Department of Energy Science, Sungkyunkwan University (SKKU), Suwon, Korea
| | - B Park
- Department of Energy Science, Sungkyunkwan University (SKKU), Suwon, Korea
- Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Korea
| | - L J Brillson
- Department of Physics, The Ohio State University, Columbus, OH, USA
- Department of Electrical and Computer Engineering, The Ohio State University, Columbus, OH, USA
| | - S H Oh
- Department of Energy Science, Sungkyunkwan University (SKKU), Suwon, Korea
| | - E Y Tsymbal
- Department of Physics and Astronomy, Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, NE, USA
| | - M S Rzchowski
- Department of Physics, University of Wisconsin-Madison, Madison, WI, USA
| | - C B Eom
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI, USA.
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Ruane WT, Johansen KM, Leedy KD, Look DC, von Wenckstern H, Grundmann M, Farlow GC, Brillson LJ. Defect segregation and optical emission in ZnO nano- and microwires. Nanoscale 2016; 8:7631-7637. [PMID: 26987850 DOI: 10.1039/c5nr08248j] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The spatial distribution of defect related deep band emission has been studied in zinc oxide (ZnO) nano- and microwires using depth resolved cathodoluminescence spectroscopy (DRCLS) in a hyperspectral imaging (HSI) mode within a UHV scanning electron microscope (SEM). Three sets of wires were examined that had been grown by pulsed laser deposition or vapor transport methods and ranged in diameter from 200 nm-2.7 μm. This data was analyzed by developing a 3D DRCLS simulation and using it to estimate the segregation depth and decay profile of the near surface defects. We observed different dominant defects from each growth process as well as diameter-dependent defect segregation behavior.
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Affiliation(s)
- W T Ruane
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA.
| | - K M Johansen
- University of Oslo, Centre for Materials Science and Nanotechnology, 0318 Oslo, Norway
| | - K D Leedy
- Air Force Research Laboratory, Sensors Directorate, WPAFB, OH 45433, USA
| | - D C Look
- Air Force Research Laboratory, Sensors Directorate, WPAFB, OH 45433, USA and Semiconductor Research Center, Wright State University, Dayton, OH 45435, USA
| | - H von Wenckstern
- Institut für Experimentelle Physik II, Universität Leipzig, Linnéstr. 5, 04103 Leipzig, Germany
| | - M Grundmann
- Institut für Experimentelle Physik II, Universität Leipzig, Linnéstr. 5, 04103 Leipzig, Germany
| | - G C Farlow
- Department of Physics, Wright State University, Dayton, OH 45435, USA
| | - L J Brillson
- Department of Physics and Department of Electrical & Computer Engineering, The Ohio State University, Columbus, OH 43210, USA
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Rutkowski MM, McNicholas KM, Zeng Z, Brillson LJ. Design of an ultrahigh vacuum transfer mechanism to interconnect an oxide molecular beam epitaxy growth chamber and an x-ray photoemission spectroscopy analysis system. Rev Sci Instrum 2013; 84:065105. [PMID: 23822376 DOI: 10.1063/1.4804195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We designed a mechanism and the accompanying sample holders to transfer between a VEECO 930 oxide molecular beam epitaxy (MBE) and a PHI Versa Probe X-ray photoemission spectroscopy (XPS) chamber within a multiple station growth, processing, and analysis system through ultrahigh vacuum (UHV). The mechanism consists of four parts: (1) a platen compatible with the MBE growth stage, (2) a platen compatible with the XPS analysis stage, (3) a sample coupon that is transferred between the two platens, and (4) the accompanying UHV transfer line. The mechanism offers a robust design that enables transfer back and forth between the growth chamber and the analysis chamber, and yet is flexible enough to allow transfer between standard sample holders for thin film growth and masked sample holders for making electrical contacts and Schottky junctions, all without breaking vacuum. We used this mechanism to transfer a barium strontium titanate thin film into the XPS analysis chamber and performed XPS measurements before and after exposing the sample to the air. After air exposure, a thin overlayer of carbon was found to form and a significant shift (~1 eV) in the core level binding energies was observed.
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Affiliation(s)
- M M Rutkowski
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA
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Vitomirov IM, Raisanen A, Finnefrock AC, Viturro RE, Brillson LJ, Kirchner PD, Pettit GD, Woodall JM. Geometric ordering, surface chemistry, band bending, and work function at decapped GaAs(100) surfaces. Phys Rev B Condens Matter 1992; 46:13293-13302. [PMID: 10003372 DOI: 10.1103/physrevb.46.13293] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Chang S, Vitomirov IM, Brillson LJ, Mailhiot C, Rioux DF, Kime YJ, Kirchner PD, Pettit GD, Woodall JM. Chemical and electronic properties of Al/. Phys Rev B Condens Matter 1992; 45:13438-13451. [PMID: 10001430 DOI: 10.1103/physrevb.45.13438] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Chang S, Vitomirov IM, Brillson LJ, Rioux DF, Kirchner PD, Pettit GD, Woodall JM. Correlation of deep-level and chemically-active-site densities at vicinal GaAs(100)-Al interfaces. Phys Rev B Condens Matter 1991; 44:1391-1394. [PMID: 9999662 DOI: 10.1103/physrevb.44.1391] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Chang S, Vitomirov IM, Brillson LJ, Rioux DF, Kirchner PD, Pettit GD, Woodall JM, Hecht MH. Erratum: Confirmation of the temperature-dependent photovoltaic effect on Fermi-level measurements by photoemission spectroscopy. Phys Rev B Condens Matter 1990; 42:7261. [PMID: 9994860 DOI: 10.1103/physrevb.42.7261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Chang S, Vitomirov IM, Brillson LJ, Rioux DF, Kirchner PD, Pettit GD, Woodall JM, Hecht MH. Confirmation of the temperature-dependent photovoltaic effect on Fermi-level measurements by photoemission spectroscopy. Phys Rev B Condens Matter 1990; 41:12299-12302. [PMID: 9993693 DOI: 10.1103/physrevb.41.12299] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Chiaradia P, Fanfoni M, Nataletti P, Brillson LJ, Slade ML, Viturro RE, Kilday D, Margaritondo G. Fermi-level pinning and intrinsic surface states in cleaved GaP. Phys Rev B Condens Matter 1989; 39:5128-5131. [PMID: 9948902 DOI: 10.1103/physrevb.39.5128] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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