Morphology and X-Ray Diffraction Peak Widths of Aluminum Nitride Single  Crystals Prepared by the Sublimation Method

Tanaka, Motoyuki; Nakahata, Seiji; Sogabe, Kouichi; Nakata, Hirohiko; Tobioka, Masaaki

doi:10.1143/jjap.36.l1062

Cited by 114 publications

(53 citation statements)

References 22 publications

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“…[18][19][20][21] The fitting of the energy versus unit-cell volume data set was performed by using the Birch-Murnaghan 22 equation of state and gave a bulk modulus of 207.7 GPa ͑BЈ = 4.158͒, which is also in a remarkable agreement with the experimental value of 207.9 GPa. 17 The computations of SXE spectra were carried out within the so-called final-state rule, 23 where no core hole was created at the photoexcited atom. Theoretical emission spectra were computed at the converged ground-state density by multiplying the orbital projected pDOS with the energydependent dipole matrix-element between the core and the valence-band states.…”

Section: Ab Initio Calculation Of Soft X-ray Absorption and Emismentioning

confidence: 99%

Electronic structure and chemical bonding anisotropy investigation of wurtzite AlN

et al. 2009

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The electronic structure and the anisotropy of the AlN and chemical bonding of wurtzite AlN has been investigated by bulk-sensitive total fluorescence yield absorption and soft x-ray emission spectroscopies. The measured N K, Al L 1 , and Al L 2,3 x-ray emission and N 1s x-ray absorption spectra are compared with calculated spectra using first-principles density-functional theory including dipole transition matrix elements. The main N 2p-Al 3p-Al 3d and N 2p-Al 3s hyridization regions are identified at −1.0 to −1.8 eV and −5.0 to −5.5 eV below the top of the valence band, respectively. In addition, N 2s-Al 3p and N 2s-Al 3s hybridization regions are found at the bottom of the valence band around −13.5 and −15 eV, respectively. A strongly modified spectral shape of Al 3s states in the Al L 2,3 emission from AlN in comparison to Al metal is found, which is also reflected in the N 2p-Al 3p hybridization observed in the Al L 1 emission. The differences between the electronic structure and chemical bonding of AlN and Al metal are discussed in relation to the position of the hybridization regions and the valence-band edge influencing the magnitude of the large band gap.

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Section: Ab Initio Calculation Of Soft X-ray Absorption and Emismentioning

confidence: 99%

Electronic structure and chemical bonding anisotropy investigation of wurtzite AlN

et al. 2009

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“…Currently, several groups are developing various techniques for the growth of bulk AlN crystals. [1][2][3][4][5][6][7][8] Recent reports of homoepitaxial layer growth and device fabrication using bulk AlN substrates have already demonstrated potential applications. [6][7][8] Despite recent progress made in nitride epilayers and devices on AlN substrates, critical issues remain.…”

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confidence: 99%

The origin of 2.78 eV emission and yellow coloration in bulk AlN substrates

Sedhain

Du²,

Edgar³

et al. 2009

Applied Physics Letters

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The yellow color of bulk AlN crystals was found to be caused by the optical absorption of light with wavelengths shorter than that of yellow. This yellow impurity limits UV transparency and hence restricts the applications of AlN substrates for deep UV optoelectronic devices. Here, the optical properties of AlN epilayers, polycrystalline AlN, and bulk AlN single crystals have been investigated using photoluminescence ͑PL͒ spectroscopy to address the origin of this yellow appearance. An emission band with a linewidth of ϳ0.3 eV ͑at 10 K͒ was observed at ϳ2.78 eV. We propose that the origin of the yellow color in bulk AlN is due to a band-to-impurity absorption involving the excitation of electrons from the valence band to the doubly negative charged state, ͑V Al 2− ͒, of isolated aluminum vacancies, ͑V Al ͒ 3−/2− described by V Al 2− +h =V Al 3− +h + . In such a context, the reverse process is responsible for the 2.78 eV PL emission.

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“…The TEM sample was prepared using a focused ion beam method. Two types of g/3g weak-beam dark-field TEM images taken near the AlN [11][12][13][14][15][16][17][18][19][20] zone axis with g = [10-10] and [0002] were obtained to determine the type of dislocation in the AlN sputtered layer. Here, g is a reciprocal lattice vector of the diffraction plane.…”

Section: Methodsmentioning

confidence: 99%

“…The lattice constants for the AlN layers sputtered with 40 and 50 vol% N 2 are indicated with black circles and white diamonds, respectively. The lattice constant along the c-axis of bulk AlN is 0.4980 nm, 18 while that of the nitrided sapphire substrate is 0.4991 nm (calculated from Fig. 3) and is represented as dashed lines in Fig.…”

Section: Lattice Constant Along the C-axismentioning

confidence: 99%

Influence of substrate temperature on the crystalline quality of AlN layers deposited by RF reactive magnetron sputtering

2015

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Aluminum nitride (AlN) is a promising material for use in applications such as ultraviolet light-emitting diodes and surface acoustic wave devices. In this study, AlN layers were fabricated on nitrided sapphire substrates using radio-frequency (RF) reactive magnetron sputtering. An AlN layer sputtered in 50 vol% N2 with a sputter power of 900 W at 823 K exhibited X-ray rocking curves for AlN (0002) and (10-12) with the best full width at half-maximum of 61 and 864 arcsec, respectively. The c-axis lattice constant of the AlN layers expanded with increasing substrate temperature because of the peening effect and thermal expansion difference between the AlN layer and sapphire substrate. Based on the results obtained here combined with those of our previous studies, a model explaining the roles of sputtering parameters in AlN layer growth using RF reactive sputtering was developed.

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Morphology and X-Ray Diffraction Peak Widths of Aluminum Nitride Single Crystals Prepared by the Sublimation Method

Cited by 114 publications

References 22 publications

Electronic structure and chemical bonding anisotropy investigation of wurtzite AlN

Electronic structure and chemical bonding anisotropy investigation of wurtzite AlN

The origin of 2.78 eV emission and yellow coloration in bulk AlN substrates

Influence of substrate temperature on the crystalline quality of AlN layers deposited by RF reactive magnetron sputtering

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