1
|
Wang R, Schultz T, Papadogianni A, Longhi E, Gatsios C, Zu F, Zhai T, Barlow S, Marder SR, Bierwagen O, Amsalem P, Koch N. Tuning the Surface Electron Accumulation Layer of In 2 O 3 by Adsorption of Molecular Electron Donors and Acceptors. Small 2023; 19:e2300730. [PMID: 37078833 DOI: 10.1002/smll.202300730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 03/23/2023] [Indexed: 05/03/2023]
Abstract
In2 O3 , an n-type semiconducting transparent transition metal oxide, possesses a surface electron accumulation layer (SEAL) resulting from downward surface band bending due to the presence of ubiquitous oxygen vacancies. Upon annealing In2 O3 in ultrahigh vacuum or in the presence of oxygen, the SEAL can be enhanced or depleted, as governed by the resulting density of oxygen vacancies at the surface. In this work, an alternative route to tune the SEAL by adsorption of strong molecular electron donors (specifically here ruthenium pentamethylcyclopentadienyl mesitylene dimer, [RuCp*mes]2 ) and acceptors (here 2,2'-(1,3,4,5,7,8-hexafluoro-2,6-naphthalene-diylidene)bis-propanedinitrile, F6 TCNNQ) is demonstrated. Starting from an electron-depleted In2 O3 surface after annealing in oxygen, the deposition of [RuCp*mes]2 restores the accumulation layer as a result of electron transfer from the donor molecules to In2 O3 , as evidenced by the observation of (partially) filled conduction sub-bands near the Fermi level via angle-resolved photoemission spectroscopy, indicating the formation of a 2D electron gas due to the SEAL. In contrast, when F6 TCNNQ is deposited on a surface annealed without oxygen, the electron accumulation layer vanishes and an upward band bending is generated at the In2 O3 surface due to electron depletion by the acceptor molecules. Hence, further opportunities to expand the application of In2 O3 in electronic devices are revealed.
Collapse
Affiliation(s)
- Rongbin Wang
- Institut für Physik and IRIS Adlershof, Humboldt-Universität zu Berlin, 12489, Berlin, Germany
| | - Thorsten Schultz
- Institut für Physik and IRIS Adlershof, Humboldt-Universität zu Berlin, 12489, Berlin, Germany
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 12489, Berlin, Germany
| | - Alexandra Papadogianni
- Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e.V, 10117, Berlin, Germany
| | - Elena Longhi
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, 30332-0400, USA
| | - Christos Gatsios
- Institut für Physik and IRIS Adlershof, Humboldt-Universität zu Berlin, 12489, Berlin, Germany
| | - Fengshuo Zu
- Institut für Physik and IRIS Adlershof, Humboldt-Universität zu Berlin, 12489, Berlin, Germany
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 12489, Berlin, Germany
| | - Tianshu Zhai
- Institut für Physik and IRIS Adlershof, Humboldt-Universität zu Berlin, 12489, Berlin, Germany
| | - Stephen Barlow
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, 30332-0400, USA
- Renewable and Sustainable Energy Institute, University of Colorado Boulder, Boulder, CO, 80303, USA
| | - Seth R Marder
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, 30332-0400, USA
- Renewable and Sustainable Energy Institute, University of Colorado Boulder, Boulder, CO, 80303, USA
- Department of Chemical and Biological Engineering and Department of Chemistry, University of Colorado Boulder, Boulder, CO, 80303, USA
| | - Oliver Bierwagen
- Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e.V, 10117, Berlin, Germany
| | - Patrick Amsalem
- Institut für Physik and IRIS Adlershof, Humboldt-Universität zu Berlin, 12489, Berlin, Germany
| | - Norbert Koch
- Institut für Physik and IRIS Adlershof, Humboldt-Universität zu Berlin, 12489, Berlin, Germany
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 12489, Berlin, Germany
| |
Collapse
|
2
|
Xu T, Zhang H, Ye M, Zhu Y, Yuan D, Li W, Zhou Y, Sun L. Controllable fabrication of hollow In 2O 3 nanoparticles by electron beam irradiation. Nanoscale 2022; 14:12569-12573. [PMID: 35975472 DOI: 10.1039/d2nr03276g] [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: 06/15/2023]
Abstract
A growth strategy is presented for controllable fabrication of hollow In2O3 nanoparticles (NPs) via oxidation of In nanocrystals under electron beam irradiation. The morphology of the NPs can be tailored by changing the electron beam energy and current density. Yolk-shell NPs are preferentially formed under 200 keV electron beam irradiation, while hollow NPs are preferentially formed at 300 keV. This work confirms that electron beam irradiation is a valuable method for the engineering and modification of nanomaterials.
Collapse
Affiliation(s)
- Tao Xu
- SEU-FEI Nano-Pico Center, Key Lab of MEMS of Ministry of Education, Southeast University, Nanjing 210096, P. R. China.
| | - Hao Zhang
- SEU-FEI Nano-Pico Center, Key Lab of MEMS of Ministry of Education, Southeast University, Nanjing 210096, P. R. China.
| | - Mao Ye
- SEU-FEI Nano-Pico Center, Key Lab of MEMS of Ministry of Education, Southeast University, Nanjing 210096, P. R. China.
| | - Yatong Zhu
- SEU-FEI Nano-Pico Center, Key Lab of MEMS of Ministry of Education, Southeast University, Nanjing 210096, P. R. China.
| | - Dundong Yuan
- SEU-FEI Nano-Pico Center, Key Lab of MEMS of Ministry of Education, Southeast University, Nanjing 210096, P. R. China.
| | - Wei Li
- SEU-FEI Nano-Pico Center, Key Lab of MEMS of Ministry of Education, Southeast University, Nanjing 210096, P. R. China.
| | - Yilong Zhou
- Thermo Fisher Shanghai Nanoport, Thermo Fisher Electronic Technology Research and Development (Shanghai) Co., Ltd., Shanghai, 201203, P. R. China
| | - Litao Sun
- SEU-FEI Nano-Pico Center, Key Lab of MEMS of Ministry of Education, Southeast University, Nanjing 210096, P. R. China.
| |
Collapse
|
3
|
Wendel P, Dietz D, Deuermeier J, Klein A. Reversible Barrier Switching of ZnO/RuO 2 Schottky Diodes. Materials (Basel) 2021; 14:2678. [PMID: 34065310 PMCID: PMC8161001 DOI: 10.3390/ma14102678] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 05/11/2021] [Accepted: 05/18/2021] [Indexed: 11/17/2022]
Abstract
The current-voltage characteristics of ZnO/RuO2 Schottky diodes prepared by magnetron sputtering are shown to exhibit a reversible hysteresis behavior, which corresponds to a variation of the Schottky barrier height between 0.9 and 1.3 eV upon voltage cycling. The changes in the barrier height are attributed to trapping and de-trapping of electrons in oxygen vacancies.
Collapse
Affiliation(s)
- Philipp Wendel
- Institute of Materials Science, Technical University of Darmstadt, 64287 Darmstadt, Germany; (P.W.); (D.D.)
| | - Dominik Dietz
- Institute of Materials Science, Technical University of Darmstadt, 64287 Darmstadt, Germany; (P.W.); (D.D.)
| | - Jonas Deuermeier
- i3N/CENIMAT, Department of Materials Science, Faculty of Science and Technology, Campus de Caparica, Universidade NOVA de Lisboa and CEMOP/UNINOVA, 2829-516 Caparica, Portugal;
| | - Andreas Klein
- Institute of Materials Science, Technical University of Darmstadt, 64287 Darmstadt, Germany; (P.W.); (D.D.)
| |
Collapse
|
4
|
Swallow JEN, Palgrave RG, Murgatroyd PAE, Regoutz A, Lorenz M, Hassa A, Grundmann M, von Wenckstern H, Varley JB, Veal TD. Indium Gallium Oxide Alloys: Electronic Structure, Optical Gap, Surface Space Charge, and Chemical Trends within Common-Cation Semiconductors. ACS Appl Mater Interfaces 2021; 13:2807-2819. [PMID: 33426870 DOI: 10.1021/acsami.0c16021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The electronic and optical properties of (InxGa1-x)2O3 alloys are highly tunable, giving rise to a myriad of applications including transparent conductors, transparent electronics, and solar-blind ultraviolet photodetectors. Here, we investigate these properties for a high quality pulsed laser deposited film which possesses a lateral cation composition gradient (0.01 ≤ x ≤ 0.82) and three crystallographic phases (monoclinic, hexagonal, and bixbyite). The optical gaps over this composition range are determined, and only a weak optical gap bowing is found (b = 0.36 eV). The valence band edge evolution along with the change in the fundamental band gap over the composition gradient enables the surface space-charge properties to be probed. This is an important property when considering metal contact formation and heterojunctions for devices. A transition from surface electron accumulation to depletion occurs at x ∼ 0.35 as the film goes from the bixbyite In2O3 phase to the monoclinic β-Ga2O3 phase. The electronic structure of the different phases is investigated by using density functional theory calculations and compared to the valence band X-ray photoemission spectra. Finally, the properties of these alloys, such as the n-type dopability of In2O3 and use of Ga2O3 as a solar-blind UV detector, are understood with respect to other common-cation compound semiconductors in terms of simple chemical trends of the band edge positions and the hydrostatic volume deformation potential.
Collapse
Affiliation(s)
- Jack E N Swallow
- Stephenson Institute for Renewable Energy and Department of Physics, University of Liverpool, Liverpool L69 7ZF, U.K
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, U.K
| | - Robert G Palgrave
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, U.K
| | - Philip A E Murgatroyd
- Stephenson Institute for Renewable Energy and Department of Physics, University of Liverpool, Liverpool L69 7ZF, U.K
| | - Anna Regoutz
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, U.K
| | - Michael Lorenz
- Felix Bloch Institute for Solid State Physics, Universität Leipzig, Leipzig, Germany
| | - Anna Hassa
- Felix Bloch Institute for Solid State Physics, Universität Leipzig, Leipzig, Germany
| | - Marius Grundmann
- Felix Bloch Institute for Solid State Physics, Universität Leipzig, Leipzig, Germany
| | - Holger von Wenckstern
- Felix Bloch Institute for Solid State Physics, Universität Leipzig, Leipzig, Germany
| | - Joel B Varley
- Lawrence Livermore National Laboratory, Livermore, California 94550, United States
| | - Tim D Veal
- Stephenson Institute for Renewable Energy and Department of Physics, University of Liverpool, Liverpool L69 7ZF, U.K
| |
Collapse
|
5
|
Abstract
Stable ohmic contacts are critical to enable efficient operation of high-voltage electronic devices using ultrawide bandgap semiconductors. Here we perform, for the first time, thermally accelerated aging of Ti/Au ohmic interfaces to (010) β-Ga2O3. We find that a heavily doped semiconductor, doped n-type by Si-ion implantation, treated with reactive ion etch (RIE), results in a low specific contact resistance of ∼10-5 Ω cm2 that is stable upon accelerated thermal aging at 300 °C for 108 h. The low resistance interface is due to thermionic field emission of electrons over an inhomogeneous barrier. Scanning/transmission electron microscopy indicates that the multi-layered structure and elemental distribution across the contact interface, formed during a 1 min 470 °C post-metallization anneal, do not change noticeably over the aging period. A ∼1 nm interfacial layer is observed by high-resolution microscopy at the Ti-TiOx/Ga2O3 interface on all samples exposed to RIE, which may contribute to their excellent stability. In addition, longer-range facet-like interfacial features are observed, which may contribute to the inhomogeneous barrier. In contrast, Ti/Au junctions to moderately doped (010) Ga2O3 made with no RIE treatment exhibit a high contact resistance that increases upon accelerated aging, along with a partially lattice-matched interface. The methods used here to understand the process, structure, and electrical property relationships for Ti/Au contact interfaces to β-Ga2O3 can be applied to assess and tune the stability of a variety of other oxide-semiconductor interfaces.
Collapse
Affiliation(s)
- Ming-Hsun Lee
- Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136, United States
| | - Rebecca L Peterson
- Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136, United States
- Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109-2122, United States
| |
Collapse
|
6
|
Abstract
As an important industrial chemical, formaldehyde is used in various fields but is harmful to health. Developing a convenient detection device for formaldehyde is significant. Based on atomically dispersed Au on In2O3 nanosheets, a formaldehyde sensor was fabricated in this work. The highly dispersed Au obtained by the ultraviolet (UV) light-assisted reduction method helps improve the sensing performance. A meager loading amount (0.01 wt %) of Au on In2O3 nanosheets exhibits high sensitivity toward ppb-level formaldehyde. Au acts as an electron sink and promotes the oxidation of formaldehyde. Atomically dispersed Au on In2O3 nanosheets decreases the activation energy and increases the number of active sites, which result in a highly efficient conversion of formaldehyde and a marked resistance change of the fabricated sensors. The selective adsorption and oxidation of formaldehyde on single atom Au's uniform sites establish excellent selectivity. Besides, the sensor exhibits short response/recovery time and excellent stability, with promising applications in formaldehyde detection.
Collapse
Affiliation(s)
- Fubo Gu
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Mengyu Di
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Dongmei Han
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Song Hong
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Zhihua Wang
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| |
Collapse
|