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Title: Thermal stability of ultra-wide-bandgap MgZnO alloys with wurtzite structure

Abstract

Mg xZn 1–xO thin films were grown as metastable alloys via a sputtering technique in order to achieve single-phase wurtzite alloys with deep-UV optical bandgaps. As-grown alloys with Mg composition range 0–72% resulted in optical bandgaps spanning the UV-range of 3.3–4.4 eV. The thermal stability of the alloys was studied via post-growth controlled annealing experiments up to 900 °C. Alloys with low Mg up to 34% were found to be highly stable and retained their optical and material properties; however, alloys with higher Mg, up to 72%, were found to be unstable and were phase separated into wurtzite and cubic structural phases with respective optical bandgaps at ~ 3.5 and 6.0 eV. Both the as-grown and annealed alloys were studied using X-ray diffraction for structural identification, transmission spectroscopy for bandgap analysis, and Raman scattering for mapping the phonon mode-behavior. The experimental value for the solubility limit was found to be ~ 30%. A straightforward model calculation based on the Raman-mode saturation behavior yielded a similar value for the solubility limit of the alloys. Furthermore, the results are discussed in terms of available phase-diagrams for stable-state ceramics alloys that were grown under thermodynamics equilibrium conditions.

Authors:
 [1];  [1];  [1];  [1];  [2];  [3]; ORCiD logo [1]
  1. Univ. of Idaho, Moscow, ID (United States)
  2. Lewis-Clark State College, Lewiston, ID (United States)
  3. Washington State Univ., Pullman, WA (United States)
Publication Date:
Research Org.:
Washington State Univ., Pullman, WA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division; USDOE
OSTI Identifier:
1463178
Alternate Identifier(s):
OSTI ID: 1489145
Grant/Contract Number:  
FG02-07ER46386
Resource Type:
Journal Article: Published Article
Journal Name:
Journal of Materials Science Materials in Electronics
Additional Journal Information:
Journal Volume: 29; Journal Issue: 19; Journal ID: ISSN 0957-4522
Publisher:
Springer
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Thapa, Dinesh, Huso, Jesse, Lapp, Jeffrey, Rajabi, Negar, Morrison, John L., McCluskey, Matthew D., and Bergman, Leah. Thermal stability of ultra-wide-bandgap MgZnO alloys with wurtzite structure. United States: N. p., 2018. Web. doi:10.1007/s10854-018-9772-y.
Thapa, Dinesh, Huso, Jesse, Lapp, Jeffrey, Rajabi, Negar, Morrison, John L., McCluskey, Matthew D., & Bergman, Leah. Thermal stability of ultra-wide-bandgap MgZnO alloys with wurtzite structure. United States. doi:10.1007/s10854-018-9772-y.
Thapa, Dinesh, Huso, Jesse, Lapp, Jeffrey, Rajabi, Negar, Morrison, John L., McCluskey, Matthew D., and Bergman, Leah. Tue . "Thermal stability of ultra-wide-bandgap MgZnO alloys with wurtzite structure". United States. doi:10.1007/s10854-018-9772-y.
@article{osti_1463178,
title = {Thermal stability of ultra-wide-bandgap MgZnO alloys with wurtzite structure},
author = {Thapa, Dinesh and Huso, Jesse and Lapp, Jeffrey and Rajabi, Negar and Morrison, John L. and McCluskey, Matthew D. and Bergman, Leah},
abstractNote = {MgxZn1–xO thin films were grown as metastable alloys via a sputtering technique in order to achieve single-phase wurtzite alloys with deep-UV optical bandgaps. As-grown alloys with Mg composition range 0–72% resulted in optical bandgaps spanning the UV-range of 3.3–4.4 eV. The thermal stability of the alloys was studied via post-growth controlled annealing experiments up to 900 °C. Alloys with low Mg up to 34% were found to be highly stable and retained their optical and material properties; however, alloys with higher Mg, up to 72%, were found to be unstable and were phase separated into wurtzite and cubic structural phases with respective optical bandgaps at ~ 3.5 and 6.0 eV. Both the as-grown and annealed alloys were studied using X-ray diffraction for structural identification, transmission spectroscopy for bandgap analysis, and Raman scattering for mapping the phonon mode-behavior. The experimental value for the solubility limit was found to be ~ 30%. A straightforward model calculation based on the Raman-mode saturation behavior yielded a similar value for the solubility limit of the alloys. Furthermore, the results are discussed in terms of available phase-diagrams for stable-state ceramics alloys that were grown under thermodynamics equilibrium conditions.},
doi = {10.1007/s10854-018-9772-y},
journal = {Journal of Materials Science Materials in Electronics},
issn = {0957-4522},
number = 19,
volume = 29,
place = {United States},
year = {2018},
month = {8}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1007/s10854-018-9772-y

Figures / Tables:

Fig. 1 Fig. 1: The XRD spectra of the samples with relatively low Mg composition: Mg0.17Zn0.83O and Mg0.34Zn0.66O. The spectra are for the as-grown samples and for samples that were annealed at 750 and 900 °C. The main diffraction peak is due to the wurtzite structure; no diffraction due to cubic structure ismore » detectable« less

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Works referenced in this record:

The deposition and annealing study of MOCVD ZnMgO
journal, April 2005