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Title: Effects of rapid thermal annealing on properties of Ga-doped Mg{sub x}Zn{sub 1−x}O films and Ga-doped Mg{sub x}Zn{sub 1−x}O/AlGaN heterojunction diodes

Abstract

This study investigated the thermal annealing effects of Ga-doped Mg{sub x}Zn{sub 1−x}O (GMZO) films and GMZO/AlGaN heterojunction diodes. GMZO films were deposited using a radio-frequency magnetron sputtering system with a 4-in. ZnO/MgO/Ga{sub 2}O{sub 3} target. In addition, the Hall results, X-ray diffraction, transparent performance, and X-ray photoelectron spectroscopy (XPS) spectra were measured. The as-grown GMZO film deposited in this study exhibited a high transparency with transmittances over 95% in the visible region (360–700 nm) and a sharp absorption edge in the UV region (275–350 nm). The phenomenon of phase separation in the GMZO films was investigated based on the XPS spectra, revealing that an increase in the O-Zn signal accompanied a decline in the O-Ga signal after the thermal annealing. Moreover, the current-voltage (I-V) characteristics of the GMZO/AlGaN n-p junction diodes were examined at different annealing temperatures. The light emission derived from the forward-biased junction and near-ultraviolet (near-UV) light emission was evident at all p-n junctions. The n-GMZO/p-AlGaN diode annealed at 800 °C exhibited a brighter near-UV emission compared with the other diodes. In addition, the spectrum of diode annealed at 800 °C exhibited a broad peak at 474 nm (2.62 eV) and a tail of the emission spectrum extending to 850 nm. Based on these findings,more » the GMZO films are suitable for forming transparent contact layers in optoelectronic devices, and the n-GMZO/p-AlGaN junction diode is a feasible alternative in near-UV light emission devices.« less

Authors:
 [1];  [2];  [1]
  1. Department of Electronics Engineering, Vanung University, Chung-Li 32061, Taiwan (China)
  2. (China)
Publication Date:
OSTI Identifier:
22314590
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 6; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ANNEALING; DOPED MATERIALS; ELECTRIC CONDUCTIVITY; EMISSION; EMISSION SPECTRA; FILMS; GALLIUM OXIDES; HETEROJUNCTIONS; JUNCTION DIODES; MAGNESIUM OXIDES; MAGNETRONS; PERFORMANCE; P-N JUNCTIONS; RADIOWAVE RADIATION; SPUTTERING; ULTRAVIOLET RADIATION; X-RAY DIFFRACTION; X-RAY PHOTOELECTRON SPECTROSCOPY

Citation Formats

Hsueh, Kuang-Po, E-mail: kphsueh@alumni.ncu.edu.tw, E-mail: kphsueh@mail.vnu.edu.tw, Department of Digital Multimedia Technology, Vanung University, Chung-Li 32061, Taiwan, and Cheng, Po-Wei. Effects of rapid thermal annealing on properties of Ga-doped Mg{sub x}Zn{sub 1−x}O films and Ga-doped Mg{sub x}Zn{sub 1−x}O/AlGaN heterojunction diodes. United States: N. p., 2014. Web. doi:10.1063/1.4892591.
Hsueh, Kuang-Po, E-mail: kphsueh@alumni.ncu.edu.tw, E-mail: kphsueh@mail.vnu.edu.tw, Department of Digital Multimedia Technology, Vanung University, Chung-Li 32061, Taiwan, & Cheng, Po-Wei. Effects of rapid thermal annealing on properties of Ga-doped Mg{sub x}Zn{sub 1−x}O films and Ga-doped Mg{sub x}Zn{sub 1−x}O/AlGaN heterojunction diodes. United States. doi:10.1063/1.4892591.
Hsueh, Kuang-Po, E-mail: kphsueh@alumni.ncu.edu.tw, E-mail: kphsueh@mail.vnu.edu.tw, Department of Digital Multimedia Technology, Vanung University, Chung-Li 32061, Taiwan, and Cheng, Po-Wei. Thu . "Effects of rapid thermal annealing on properties of Ga-doped Mg{sub x}Zn{sub 1−x}O films and Ga-doped Mg{sub x}Zn{sub 1−x}O/AlGaN heterojunction diodes". United States. doi:10.1063/1.4892591.
@article{osti_22314590,
title = {Effects of rapid thermal annealing on properties of Ga-doped Mg{sub x}Zn{sub 1−x}O films and Ga-doped Mg{sub x}Zn{sub 1−x}O/AlGaN heterojunction diodes},
author = {Hsueh, Kuang-Po, E-mail: kphsueh@alumni.ncu.edu.tw, E-mail: kphsueh@mail.vnu.edu.tw and Department of Digital Multimedia Technology, Vanung University, Chung-Li 32061, Taiwan and Cheng, Po-Wei},
abstractNote = {This study investigated the thermal annealing effects of Ga-doped Mg{sub x}Zn{sub 1−x}O (GMZO) films and GMZO/AlGaN heterojunction diodes. GMZO films were deposited using a radio-frequency magnetron sputtering system with a 4-in. ZnO/MgO/Ga{sub 2}O{sub 3} target. In addition, the Hall results, X-ray diffraction, transparent performance, and X-ray photoelectron spectroscopy (XPS) spectra were measured. The as-grown GMZO film deposited in this study exhibited a high transparency with transmittances over 95% in the visible region (360–700 nm) and a sharp absorption edge in the UV region (275–350 nm). The phenomenon of phase separation in the GMZO films was investigated based on the XPS spectra, revealing that an increase in the O-Zn signal accompanied a decline in the O-Ga signal after the thermal annealing. Moreover, the current-voltage (I-V) characteristics of the GMZO/AlGaN n-p junction diodes were examined at different annealing temperatures. The light emission derived from the forward-biased junction and near-ultraviolet (near-UV) light emission was evident at all p-n junctions. The n-GMZO/p-AlGaN diode annealed at 800 °C exhibited a brighter near-UV emission compared with the other diodes. In addition, the spectrum of diode annealed at 800 °C exhibited a broad peak at 474 nm (2.62 eV) and a tail of the emission spectrum extending to 850 nm. Based on these findings, the GMZO films are suitable for forming transparent contact layers in optoelectronic devices, and the n-GMZO/p-AlGaN junction diode is a feasible alternative in near-UV light emission devices.},
doi = {10.1063/1.4892591},
journal = {Journal of Applied Physics},
number = 6,
volume = 116,
place = {United States},
year = {Thu Aug 14 00:00:00 EDT 2014},
month = {Thu Aug 14 00:00:00 EDT 2014}
}
  • 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
  • In the paper, the photoluminescence (PL) measurements, current–voltage–temperature (I-V-T) measurements, space charge techniques (C-V and deep level transient spectroscopy (DLTS)), and photocurrent spectral characteristics have been applied to investigate defects in p-Si/MgO/ n-Zn{sub 1−x}Mg{sub x}O heterojunction (HJ). The HJ structure was grown on p-type Si (111) substrate with resistivity equal to 0.1 Ω cm by the plasma-assisted molecular beam epitaxy technique. A radio-frequency cell was used for the generation of oxygen plasma. PL spectrum let us determine the Mg content ∼10%. Besides the excitonic Zn{sub 0.9}Mg{sub 0.1}O line, the PL spectrum also contains green and yellow emission bands indicating themore » presence of defect states in the investigated structures. I-V measurements reveal the rectifying properties of the HJ and the current thermally activated with a trap with the activation energy equal to 0.42 eV. DLTS studies yield the majority trap of the activation energy 0.42 eV, confirming the result obtained from the I-V measurements. It was found that the defects related to this trap have a point like behaviour. A spectral characteristic of the photocurrent shows that the p-Si/MgO/n-Zn{sub 1−x}Mg{sub x}O HJ may be applied as a photodiode operating within the wavelength range of 300 nm-1100 nm. The dark current transport and photocurrent spectrum were explained using the Anderson model of a HJ.« less
  • Thermal annealing influence on properties of strontium-barium niobate (SBN) films doped with Eu{sup 3+} has been studied using laser spectroscopic methods. The Stark splittings of the {sup 5}D{sub 1} state and all the {sup 7}F{sub J} states are well resolved only in the spectra from the annealed films, whereas the spectra of Eu{sup 3+} in the as-deposited film is similar to that in amorphous phases. Non-resonant fluorescence line narrowing (FLN) is observed only for the annealed film, which indicates a correlation between the energy levels of Eu{sup 3+} in inhomogeneous line broadening. Annealing-induced crystallization of the as-deposited film also increasesmore » the {sup 5}D{sub 0} fluorescence lifetime and allows hyperfine spectral hole burning.« less
  • Solid solution nanocrystals of gallium nitride–zinc oxide have been realized as potential photocatalysts for visible light driven overall water splitting. The band gap of these materials has been found to narrow further into the visible region as a function of increasing zinc oxide concentration, and thus, it is desirable to synthesize zinc oxide-rich gallium nitride–zinc oxide solid solutions. In this paper, we discuss the effects of using nitridation temperature to control zinc oxide content on the electronic and chemical properties of gallium nitride–zinc oxide solid solution nanostructures. The effect of nitridation temperature was studied using X-ray absorption fine structure (XAFS),more » including both X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS), and X-ray excited optical luminescence (XEOL). It was determined that using nitridation temperature as a method of controlling zinc oxide concentration results in solid solutions with poor crystallinity, phase separation, and mixed surface oxide formation. These findings suggest that many complications arise from using nitridation temperature to control zinc oxide concentration in gallium nitride–zinc oxide solid solutions, and thus, it is possible that the resultant materials would exhibit poor photocatalytic activity.« less