A Reinvestigation of β-Gallium Oxide

Åhman, Jens; Svensson, Gunnar; Albertsson, J.

doi:10.1107/s0108270195016404

Cited by 437 publications

(302 citation statements)

References 6 publications

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“…The 1/e 2 radii (where beam diameter is defined by the intensity falls to 1/e 2 = 0.135 times the maximum value) of the pump and probe beams incident on the Al film surface were 30 µm and 5 µm, respectively. The modulation frequency of the pump beam was set to 5 …”

Section: B Tdtr Measurement Methods and Heat Capacity Measurementmentioning

confidence: 99%

“…Efficient removal of the generated heat is required for maintaining the performance, and also for ensuring the reliability of the device. β-Ga 2 O 3 crystallizes in a highly anisotropic monoclinic crystal structure with the space group C2/m and lattice constants of a = 12.214 Å, b = 3.0371 Å, c = 5.7981 Å, and β=103.83º 5 . Because of this crystalline anisotropy, the thermal conductivity in β-Ga 2 O 3 is expected to be different along different crystal directions.…”

Section: Introductionmentioning

confidence: 99%

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Anisotropic thermal conductivity in single crystal β-gallium oxide

Guo

Verma

et al. 2015

Applied Physics Letters

427

263

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The thermal conductivities of β-Ga 2 O 3 single crystals along four different crystal directions were measured in the temperature range of 80-495K using the time domain thermoreflectance (TDTR) method. A large anisotropy was found. At room temperature, the [010] direction has the highest thermal conductivity of 27.0±2 .0 W/mK, while that along the [100] direction has the lowest value of 10.9±1.0 W/mK. At high temperatures, the thermal conductivity follows a ~1/T relationship characteristic of Umklapp phonon scattering, indicating phonon-dominated heat transport in the β-Ga 2 O 3 crystal. The measured experimental thermal conductivity is supported by first-principles calculations which suggest that the anisotropy in thermal conductivity is due to the differences of the speed of sound along different crystal directions.

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Section: B Tdtr Measurement Methods and Heat Capacity Measurementmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Anisotropic thermal conductivity in single crystal β-gallium oxide

Guo

Verma

et al. 2015

Applied Physics Letters

427

263

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“…In order to examine for the potential existence of gallium oxynitrides and the solubility of nitrogen in b-Ga 2 O 3 we have chosen the ammonolysis of b-Ga 2 O 3 , which is an established Ahman et al [27]. route of converting gallium oxide into gallium nitride (see [30] as an example).…”

Section: Methodsmentioning

confidence: 99%

On the ammonolysis of Ga2O3: An XRD, neutron diffraction and XAS investigation of the oxygen-rich part of the system Ga2O3–GaN

Roehrens

Brendt

Samuelis

et al. 2010

Journal of Solid State Chemistry

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GaN Ammonolysis Oxynitrides Nitrogen solubility a b s t r a c tWe investigated the ammonolysis of b-Ga 2 O 3 at elevated temperatures by means of ex situ X-ray diffraction, ex situ neutron diffraction and in situ X-ray absorption spectroscopy. Within the detection limits of these methods, we can rule out the existence of a crystalline or amorphous oxynitride phase that is not derived from wurtzite-type GaN. No evidence for a b-Ga 2 O 3 related oxynitride phase was found, and the nitrogen solubility in b-Ga 2 O 3 was found to be below the detection limit of about 2-3 at% in the anionic sublattice. These findings were obtained by monitoring the anionic occupancy factors and the lattice parameters of the b-Ga 2 O 3 phase obtained from total diffraction pattern refinement with the Rietveld method and by linear combination fitting of the X-ray absorption spectra that were recorded during the ammonolysis.

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“…4 The high-temperature structure 4,5 of Ga 2 O 3 (␤ form) is monoclinic (space group C2/m), with the lattice parameters a ϭ 12.214, b ϭ 3.037, c ϭ 5.798 Å, ␤ ϭ 103.83°. 6 ␤-Ga 2 O 3 is only one of five well-known forms [7][8][9] of gallium oxide: ␣-, -, ␦-, and ε-Ga 2 O 3 , and all of these polymorphs are converted to ␤-Ga 2 O 3 at T Ͼ 870°C. 10 Growth of the single crystals 11 of ␤-Ga 2 O 3 has been studied by Okada et al, 12 using the tin-flux method, and Ga 2 O 3 nanowires were prepared by Zhang et al 13 and Choi et al 14 Manufacture of n-type semiconducting Ga 2 O 3 thin films on electrically insulating substrates has been studied by Meixner et al, 15 which are considered and developed for the detection of reducing gases.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Gallium Oxide Hydroxide Crystals in Aqueous Solutions with or without Urea and Their Calcination Behavior

Taş

Majewski

Aldinger

2002

Journal of the American Ceramic Society

163

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Gallium oxide hydroxide (GaOOH⅐xH 2 O) single crystals were synthesized in aqueous solutions by using two different precipitation techniques: homogeneous decomposition of urea and forced hydrolysis in pure water. Precipitation of crystals started at exactly the same pH value (i.e., 2.05 at 85°C) in both cases. The morphology of crystals turned out to be quite different (zeppelin-like with urea, rodlike without urea) in each of the above methods. Calcination of these gallium oxide hydroxide crystals in air at temperatures >500°C transformed them into Ga 2 O 3 . Characterization of the samples was performed by X-ray diffractometry, scanning electron microscopy, thermogravimetry/differential thermal analysis, Fourier transform infrared spectroscopy, and ICP, carbon, and nitrogen analyses.

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A Reinvestigation of β-Gallium Oxide

Cited by 437 publications

References 6 publications

Anisotropic thermal conductivity in single crystal β-gallium oxide

Anisotropic thermal conductivity in single crystal β-gallium oxide

On the ammonolysis of Ga2O3: An XRD, neutron diffraction and XAS investigation of the oxygen-rich part of the system Ga2O3–GaN

Synthesis of Gallium Oxide Hydroxide Crystals in Aqueous Solutions with or without Urea and Their Calcination Behavior

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