TY - JOUR
T1 - Infrared dielectric functions and Brillouin zone center phonons of
AU - Stokey, Megan
AU - Korlacki, Rafał
AU - Hilfiker, Matthew
AU - Knight, Sean
AU - Richter, Steffen
AU - Darakchieva, Vanya
AU - Jinno, Riena
AU - Cho, Yongjin
AU - Xing, Huili Grace
AU - Jena, Debdeep
AU - Oshima, Yuichi
AU - Khan, Kamruzzaman
AU - Ahmadi, Elaheh
AU - Schubert, Mathias
N1 - Funding Information:
This work was supported in part by the National Science Foundation (NSF) under Awards No. NSF DMR 1808715 and No. NSF/EPSCoR RII Track-1: Emergent Quantum Materials and Technologies (EQUATE), Award No. OIA-2044049, and by Air Force Office of Scientific Research under Awards No. FA9550-18-1-0360, No. FA9550-19-S-0003, and No. FA9550-21-1-0259, and by ACCESS, an AFOSR Center of Excellence, under Award No. FA9550-18-1-0529, and by the Knut and Alice Wallenbergs Foundation award Wide-Bandgap Semiconductors for Next Generation Quantum Components. M.S. acknowledges the University of Nebraska Foundation and the J. A. Woollam Foundation for support. R.J. acknowledges the supported by JSPS Overseas Challenge Program for Young Researchers 1080033. This work was also supported in part by the Swedish Research Council VR Award No. 2016-00889, the Swedish Foundation for Strategic Research Grants No. RIF14-055 and No. EM16-0024, by the Swedish Governmental Agency for Innovation Systems VINNOVA under the Competence Center Program Grant No. 201605190, and by the Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linköping University, Faculty Grant SFO Mat LiU No. 2009-00971.
Publisher Copyright:
© 2022 American Physical Society
PY - 2022/1
Y1 - 2022/1
N2 - We determine the anisotropic dielectric functions of rhombohedral α-Ga2O3 by far-infrared and infrared generalized spectroscopic ellipsometry and derive all transverse optical and longitudinal optical phonon mode frequencies and broadening parameters. We also determine the high-frequency and static dielectric constants. We perform density functional theory computations and determine the phonon dispersion for all branches in the Brillouin zone, and we derive all phonon mode parameters at the Brillouin zone center including Raman-active, infrared-active, and silent modes. Excellent agreement is obtained between our experimental and computation results as well as among all previously reported partial information from experiment and theory. We also compute the same information for α-Al2O3, the binary parent compound for the emerging alloy of α-(AlxGa1−x)2O3, and use results from previous investigations [Schubert, Tiwald, and Herzinger, Phys. Rev. B 61, 8187 (2000)10.1103/PhysRevB.61.8187] to compare all properties among the two isostructural compounds. From both experimental and theoretical investigations, we compute the frequency shifts of all modes between the two compounds. Additionally, we calculate overlap parameters between phonon mode eigenvectors and discuss the possible evolution of all phonon modes into the ternary alloy system and whether modes may form single-mode or more complex mode behaviors.
AB - We determine the anisotropic dielectric functions of rhombohedral α-Ga2O3 by far-infrared and infrared generalized spectroscopic ellipsometry and derive all transverse optical and longitudinal optical phonon mode frequencies and broadening parameters. We also determine the high-frequency and static dielectric constants. We perform density functional theory computations and determine the phonon dispersion for all branches in the Brillouin zone, and we derive all phonon mode parameters at the Brillouin zone center including Raman-active, infrared-active, and silent modes. Excellent agreement is obtained between our experimental and computation results as well as among all previously reported partial information from experiment and theory. We also compute the same information for α-Al2O3, the binary parent compound for the emerging alloy of α-(AlxGa1−x)2O3, and use results from previous investigations [Schubert, Tiwald, and Herzinger, Phys. Rev. B 61, 8187 (2000)10.1103/PhysRevB.61.8187] to compare all properties among the two isostructural compounds. From both experimental and theoretical investigations, we compute the frequency shifts of all modes between the two compounds. Additionally, we calculate overlap parameters between phonon mode eigenvectors and discuss the possible evolution of all phonon modes into the ternary alloy system and whether modes may form single-mode or more complex mode behaviors.
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U2 - 10.1103/PhysRevMaterials.6.014601
DO - 10.1103/PhysRevMaterials.6.014601
M3 - Article
AN - SCOPUS:85122851669
VL - 6
JO - Physical Review Materials
JF - Physical Review Materials
SN - 2475-9953
IS - 1
M1 - 014601
ER -