Anisotropic Optical Spectra of α-Al2O3Single Crystals in the Vacuum Ultraviolet Region. II. Spectra of Optical Constants

Tomiki, Tetsuhiko; Ganaha, Yoshiiku; Futemma, Tomoyoshi; Shikenbaru, Tohru; Aiura, Y.; Yuri, Masatada; Sato, Shintaro; Fukutani, Hirohito; Kato, Hidemi; Miyahara, Tsuneaki; Tamashiro, Junkoh; Yonesu, Akira

doi:10.1143/jpsj.62.1372

Cited by 37 publications

(13 citation statements)

References 16 publications

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“…The ordinary dielectric function was obtained by fitting and data from all angles of incidence together in a multilayer model [56], which also accounts for the surface roughness via the Bruggeman effective medium approximation [57] and for the (0001)-oriented α-Al 2 O 3 substrate. The dielectric functions published by Malitson and Tomiki et al [58,59] for the visible-ultraviolet spectral range were used to describe the sapphire substrate. In the infrared spectral range, we determined experimentally the dielectric response of sapphire on polished sapphire substrates with different surface orientations, i.e., (0001), (1100), and (1120) orientations.…”

Section: Methodsmentioning

confidence: 99%

“…The high-energy interband transitions of sapphire were reported for a very wide spectral range [59,69,70]. Here, we use the experimental results by Tomiki and colleagues [59] and follow a later analysis by Harmann et al [68], where six characteristic transition energies were identified in the spectral range up to 18 eV for the ordinary dielectric function (Table III).…”

Section: B Optical Properties In the Visible-to-ultraviolet Spectralmentioning

confidence: 96%

“…Here, we use the experimental results by Tomiki and colleagues [59] and follow a later analysis by Harmann et al [68], where six characteristic transition energies were identified in the spectral range up to 18 eV for the ordinary dielectric function (Table III). Visual inspection of ε 2 for α-Ga 2 O 3 shows that the overall line shape is quite similar (Fig.…”

Section: B Optical Properties In the Visible-to-ultraviolet Spectralmentioning

confidence: 99%

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Ordinary dielectric function of corundumlike α−Ga2O3 from 40 meV to 20 eV

Feneberg

Nixdorf

Neumann

et al. 2018

Phys. Rev. Materials

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The linear optical response of metastable α-Ga 2 O 3 is investigated by spectroscopic ellipsometry. We determine the ordinary dielectric function from lattice vibrations up to the vacuum ultraviolet spectral range at room temperature for a sample with a (0001) surface. Three out of four E u infrared-active phonon modes are unambiguously determined, and their frequencies are in good agreement with density functional theory calculations. The dispersion of the refractive index in the visible and ultraviolet part of the spectrum is determined. High-energy interband transitions are characterized up to 20 eV. By comparison with the optical response of α-Al 2 O 3 and with theoretical results, a tentative assignment of interband transitions is proposed.

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Section: Methodsmentioning

confidence: 99%

Section: B Optical Properties In the Visible-to-ultraviolet Spectralmentioning

confidence: 96%

Section: B Optical Properties In the Visible-to-ultraviolet Spectralmentioning

confidence: 99%

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Ordinary dielectric function of corundumlike α−Ga2O3 from 40 meV to 20 eV

Feneberg

Nixdorf

Neumann

et al. 2018

Phys. Rev. Materials

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“…Other investigators 51,52 have also used a E −p power law where p is selected so that the spectral behavior of the absorption constant derived from R(E) by KK analysis conforms reasonably well to the Urbach rule. Instead of varying the exponent p, the method presented here assumes p is always 4, consistent with free electron behavior, and the principal adjustment to the data is scaling it to fit the VUV data to the ellipsometry data on the low-energy side.…”

Section: Optical Propertymentioning

confidence: 99%

Optical properties of AlN determined by vacuum ultraviolet spectroscopy and spectroscopic ellipsometry data

Jones

French

Müllejans³

et al. 1999

J. Mater. Res.

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Precise and accurate knowledge of the optical properties of aluminum nitride (AlN) in the ultraviolet (UV) and visible (VIS) regions is important because of the increasing application of AlN in optical and electro-optical devices, including compact disks, phase shift lithography masks, and AlN/GaN multilayer devices. The interband optical properties in the vacuum ultraviolet (VUV) region of 6-44 eV have been investigated previously because they convey detailed information on the electronic structure and interatomic bonding of the material. In this work, we have combined spectroscopic ellipsometry with UV/VIS and VUV spectroscopy to directly determine the optical constants of AlN in this range, thereby reducing the uncertainty in the preparation of the low-energy data extrapolation essential for Kramers-Kronig analysis of VUV reflectance. We report the complex optical properties of AlN, over the range of 1.5-42 eV, showing improved agreement with theory when contrasted with earlier results.

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“…15.5. There appears to be two sets of inconsistent data from [50] and [51], and we have chosen to use the data from [50]. We have used the data for the ordinary polarization because it has one plane of polarization as opposed to the extraordinary polarization which is only in one direction.…”

Section: Aluminum Oxide A1 2 0 3 Resultsmentioning

confidence: 99%

Quantum-coupled single-electron thermal to electric conversion scheme

Hagelstein

Chen

et al. 2009

Journal of Applied Physics

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A new thermal to electric conversion scheme based on an excitation transfer and tunneling mechanism is studied theoretically. Coulomb coupling dominates when the hot side and the cold side are very close. Two important concepts went into the device scheme: (1) Coulomb coupling, to try to increase throughput power (which is not subject to blackbody limit), and (2) a quantum dot implementation, to restrict number of states, to try to increase efficiency. Modeling efforts from Bloch equations, brute force numerical simulations, and the secular equations partitioning method are discussed. A hot-side quantum dot design of the device is considered. Alternative implementation where the hot-side is a plain sheet of metal or aluminum oxide is analyzed. We found that the model power/area is higher than the blackbody limit, and the predicted conversion efficiency is very high.

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Anisotropic Optical Spectra of α-Al₂O₃Single Crystals in the Vacuum Ultraviolet Region. II. Spectra of Optical Constants

Cited by 37 publications

References 16 publications

Ordinary dielectric function of corundumlike α−Ga2O3 from 40 meV to 20 eV

Ordinary dielectric function of corundumlike α−Ga2O3 from 40 meV to 20 eV

Optical properties of AlN determined by vacuum ultraviolet spectroscopy and spectroscopic ellipsometry data

Quantum-coupled single-electron thermal to electric conversion scheme

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