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Title: Oxygen vacancy tuned Ohmic-Schottky conversion for enhanced performance in β-Ga{sub 2}O{sub 3} solar-blind ultraviolet photodetectors

Abstract

β-Ga{sub 2}O{sub 3} epitaxial thin films were deposited using laser molecular beam epitaxy technique and oxygen atmosphere in situ annealed in order to reduce the oxygen vacancy. Metal/semiconductor/metal structured photodetectors were fabricated using as-grown film and annealed film separately. Au/Ti electrodes were Ohmic contact with the as-grown films and Schottky contact with the annealed films. In compare with the Ohmic-type photodetector, the Schottky-type photodetector takes on lower dark current, higher photoresponse, and shorter switching time, which benefit from Schottky barrier controlling electron transport and the quantity of photogenerated carriers trapped by oxygen vacancy significant decreasing.

Authors:
; ; ; ; ; ;  [1];  [2];  [3];  [1];  [2]
  1. School of Science, Beijing University of Posts and Telecommunications, Beijing 100876 (China)
  2. (China)
  3. Physics Department, The State University of New York at Potsdam, Potsdam, New York 13676-2294 (United States)
Publication Date:
OSTI Identifier:
22311106
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 105; Journal Issue: 2; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ANNEALING; CARRIERS; CONVERSION; ELECTRIC CONDUCTIVITY; ELECTRIC CONTACTS; GALLIUM OXIDES; GOLD; LASER RADIATION; METALS; MOLECULAR BEAM EPITAXY; OXYGEN; PHOTODETECTORS; SCHOTTKY BARRIER DIODES; SEMICONDUCTOR MATERIALS; THIN FILMS; TITANIUM; TRAPPING; ULTRAVIOLET RADIATION; VACANCIES

Citation Formats

Guo, D. Y., Wu, Z. P., An, Y. H., Guo, X. C., Chu, X. L., Sun, C. L., Tang, W. H., E-mail: whtang@bupt.edu.cn, State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, Li, L. H., Li, P. G., E-mail: pgli@zstu.edu.cn, and Center for Optoelectronics Materials and Devices, Department of Physics, Zhejiang Sci-Tech University, Hangzhou, 310018 Zhejiang. Oxygen vacancy tuned Ohmic-Schottky conversion for enhanced performance in β-Ga{sub 2}O{sub 3} solar-blind ultraviolet photodetectors. United States: N. p., 2014. Web. doi:10.1063/1.4890524.
Guo, D. Y., Wu, Z. P., An, Y. H., Guo, X. C., Chu, X. L., Sun, C. L., Tang, W. H., E-mail: whtang@bupt.edu.cn, State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, Li, L. H., Li, P. G., E-mail: pgli@zstu.edu.cn, & Center for Optoelectronics Materials and Devices, Department of Physics, Zhejiang Sci-Tech University, Hangzhou, 310018 Zhejiang. Oxygen vacancy tuned Ohmic-Schottky conversion for enhanced performance in β-Ga{sub 2}O{sub 3} solar-blind ultraviolet photodetectors. United States. doi:10.1063/1.4890524.
Guo, D. Y., Wu, Z. P., An, Y. H., Guo, X. C., Chu, X. L., Sun, C. L., Tang, W. H., E-mail: whtang@bupt.edu.cn, State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, Li, L. H., Li, P. G., E-mail: pgli@zstu.edu.cn, and Center for Optoelectronics Materials and Devices, Department of Physics, Zhejiang Sci-Tech University, Hangzhou, 310018 Zhejiang. Mon . "Oxygen vacancy tuned Ohmic-Schottky conversion for enhanced performance in β-Ga{sub 2}O{sub 3} solar-blind ultraviolet photodetectors". United States. doi:10.1063/1.4890524.
@article{osti_22311106,
title = {Oxygen vacancy tuned Ohmic-Schottky conversion for enhanced performance in β-Ga{sub 2}O{sub 3} solar-blind ultraviolet photodetectors},
author = {Guo, D. Y. and Wu, Z. P. and An, Y. H. and Guo, X. C. and Chu, X. L. and Sun, C. L. and Tang, W. H., E-mail: whtang@bupt.edu.cn and State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876 and Li, L. H. and Li, P. G., E-mail: pgli@zstu.edu.cn and Center for Optoelectronics Materials and Devices, Department of Physics, Zhejiang Sci-Tech University, Hangzhou, 310018 Zhejiang},
abstractNote = {β-Ga{sub 2}O{sub 3} epitaxial thin films were deposited using laser molecular beam epitaxy technique and oxygen atmosphere in situ annealed in order to reduce the oxygen vacancy. Metal/semiconductor/metal structured photodetectors were fabricated using as-grown film and annealed film separately. Au/Ti electrodes were Ohmic contact with the as-grown films and Schottky contact with the annealed films. In compare with the Ohmic-type photodetector, the Schottky-type photodetector takes on lower dark current, higher photoresponse, and shorter switching time, which benefit from Schottky barrier controlling electron transport and the quantity of photogenerated carriers trapped by oxygen vacancy significant decreasing.},
doi = {10.1063/1.4890524},
journal = {Applied Physics Letters},
number = 2,
volume = 105,
place = {United States},
year = {Mon Jul 14 00:00:00 EDT 2014},
month = {Mon Jul 14 00:00:00 EDT 2014}
}
  • Individual {beta}-Ga{sub 2}O{sub 3} nanowires as solar-blind photodetectors are investigated. The detectors show encouraging advantages to 254 nm light. The dark current is on the order of pA. The conductance of the nanowire increases by about three orders of magnitude under 254 nm ultraviolet illumination. The upper limits of the response and recovery time are 0.22 and 0.09 s, respectively. These results indicate that {beta}-Ga{sub 2}O{sub 3} nanowires have potential applications in realizing future miniaturized solar-blind photodetectors.
  • UV and deep-UV selective photodiodes from visible-blind to solar-blind were realized based on a Si-doped (In{sub x}Ga{sub 1–x}){sub 2}O{sub 3} thin film with a monotonic lateral variation of 0.0035 < x < 0.83. Such layer was deposited by employing a continuous composition spread approach relying on the ablation of a single segmented target in pulsed-laser deposition. The photo response signal is provided from a metal-semiconductor-metal structure upon backside illumination. The absorption onset was tuned from 4.83 to 3.22 eV for increasing x. Higher responsivities were observed for photodiodes fabricated from indium-rich part of the sample, for which an internal gain mechanism could be identified.
  • Highlights: • Single-phase wurtzite/cubic Mg{sub x}Zn{sub 1−x}O films were grown by RF magnetron sputtering technique. • We focus on the red-shift caused by annealing the Mg{sub x}Zn{sub 1−x}O films. • MSM-structured visible-blind and solar-blind UV photodetectors were fabricated. - Abstract: A series of single-phase Mg{sub x}Zn{sub 1−x}O films with different Mg contents were prepared on quartz substrates by RF magnetron sputtering technique using different MgZnO targets, and annealed under the atmospheric environment. The absorption edges of Mg{sub x}Zn{sub 1−x}O films can cover the whole near ultraviolet and even the whole solar-blind spectra range, and the solar-blind wurtzite/cubic Mg{sub x}Zn{sub 1−x}Omore » films have been realized successfully by the same method. In addition, the absorption edges of annealed films shift to a long wavelength, which is caused by the diffusion of Zn atoms gathering at the surface during the thermal treatment process. Finally, the truly solar-blind metal-semiconductor-metal structured photodetectors based on wurtzite Mg{sub 0.445}Zn{sub 0.555}O and cubic Mg{sub 0.728}Zn{sub 0.272}O films were fabricated. The corresponding peak responsivities are 17 mA/W at 275 nm and 0.53 mA/W at 250 nm under a 120 V bias, respectively.« less
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  • AZO interlayers between n-Ga 2O 3 and Ti/Au metallization significantly enhance Ohmic contact formation after annealing at ≥ 300°C. Without the presence of the AZO, similar anneals produce only rectifying current-voltage characteristics. Transmission Line Measurements of the Au/Ti/AZO/Ga 2O 3 stacks showed the specific contact resistance and transfer resistance decreased sharply from as-deposited values with annealing. The minimum contact resistance and specific contact resistance of 0.42 Ω-mm and 2.82 × 10 -5 Ω-cm 2 were achieved after a relatively low temperature 400°C annealing. In conclusion, the conduction band offset between AZO and Ga 2O 3 is 0.79 eV and providesmore » a favorable pathway for improved electron transport across this interface.« less