Determination of the Al mole fraction and the band gap bowing of epitaxial AlxGa1−xN films

Angerer, H.; Brunner, Daniel; Freudenberg, F.; Ambacher, O.; Stutzmann, M.; Höpler, R.; Metzger, Thomas; Born, E.; Dollinger, G.; Bergmaier, A.; Karsch, Stefan; Körner, H. J.

doi:10.1063/1.119949

Cited by 304 publications

(172 citation statements)

References 23 publications

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“…The Al x Ga 1-x N films had rms surface roughnesses between 5 and 15 nm, as obtained by atomic force microscopy. The Al molar fraction was examined by elastic recoil detection analysis (ERDA) [9]. The ERDA measurements were generaly in good agreement with estimates based on the lattice constants a 0 and c 0 (taking into account a biaxial stress, σ ≤ 0.4 GPa), obtained by high resolution X-ray diffraction (HRXRD) using Vegard's law [7], [10].…”

Section: Methodsmentioning

confidence: 79%

AlGaN-Based Bragg Reflectors

Ambacher

Arzberger

Brunner

et al. 1997

MRS Internet j. nitride semicond. res.

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We have studied the dependence of the absorption edge and the refractive index of wurtzite Al x Ga 1-x N films on composition using transmission, ellipsometry and photothermal deflection spectroscopy. The Al molar fraction of the Al x Ga 1-x N films grown by plasma-induced molecular beam epitaxy was varied through the entire range of composition (0 ≤ x ≤ 1). We determined the absorption edges of Al x Ga 1-x N films and a bowing parameter of 1.3 ± 0.2 eV. The refractive index below the bandgap was deduced from the interference fringes, the dielectric function between 2.5 and 25 eV from ellipsometry measurements. The measured absorption coefficients and refractive indices were used to calculate the design and reflectivity of AlGaN-based Bragg reflectors working in the blue and near-ultraviolet spectral region.

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Section: Methodsmentioning

confidence: 79%

AlGaN-Based Bragg Reflectors

Ambacher

Arzberger

Brunner

et al. 1997

MRS Internet j. nitride semicond. res.

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“…Removing of about 50 µm from the highly defective N-face side of the FS films results in an equalizing of the in-plane lattice parameters being much closer to the values of the reference GaN power constant (a 0 = 3.1893 Å [10]) and thus, leading to a very small difference in the in-plane strains between the two faces. The polishing of the GaN, however, could introduce additional impurities and/or structural defects.…”

Section: Effect Of Substrate Separationmentioning

confidence: 99%

Bending in HVPE GaN free‐standing films: effects of laser lift‐off, polishing and high‐pressure annealing

Paskova

Darakchieva

Paskov

et al. 2006

Phys. Status Solidi (c)

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We have studied the effects of laser lift-off and polishing processes on the bending of free-standing HVPE grown GaN thick films. Their structural characteristics were accessed by reciprocal space mapping and lattice parameters measurements as well as by Raman scattering and photoluminescence. The in-plane strain difference between the two faces was found to have determining effect on the bending of the freestanding films. Removing the high-defect-density near-interface region either by melting caused by laser lift-off, or by polishing, or by point defects dissociation caused by high-pressure annealing was found to lead to flattening of the strain distribution along the film thickness and a significant reduction of the bending of the free-standing films.

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“…8. The absolute error of the samples Al-content was declared to be maximally 5 % by Angerer et al [15].…”

Section: Coupled Lo-phonon Plasmon Modes (Lpp Modes)mentioning

confidence: 99%

“…Their thickness runs from a few nm to 1.8 µm and their free carrier concentrations (n-type) from 10 18 to 10 20 cm -3 . The investigated Al x Ga 1-x N layers with 0 < x < 1 were grown with plasma-assisted MBE on (0001) sapphire and are about 1 µm thick [14,15]. The AlN samples were fabricated by a direct reaction of aluminum vapor with nitrogen at high temperatures (1900 °C) [16,17].…”

Section: Experimental 21 Samplesmentioning

confidence: 99%

Lattice dynamics in GaN and AlN probed with first‐ and second‐order Raman spectroscopy

Haboeck

Siegle

Hoffmann

et al. 2003

phys. stat. sol. (c)

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We present a selection of our contributions to basic research on the lattice dynamical properties of group-III nitrides and their alloys. We used first-order Raman scattering to determine the zone-center phonons and their dependence on structural attributes such as stress, chemical composition, impurities, and doping. Results on the angular dispersion of the polar modes, strain distribution, coupled LO-phonon plasmon modes, multi-mode behavior in Al x Ga 1-x N, and the quantitative determination of the phase purity of cubic and hexagonal GaN are shown. Second-order Raman-scattering experiments on GaN and AlN provide information on the vibrational states throughout the entire Brillouin zone. Based on a comparison of experimental data and calculated phonon-dispersion curves we assigned the observed structures to particular phonon branches and points in the Brillouin zone. We also discuss the behavior of the optical modes under large hydrostatic pressure. 1 Introduction During the last decade group-III nitrides have been an object of increasing research because of their interesting physical properties such as an adjustable band gap (1.9 eV to 6.2 eV) by varying the composition of the alloys [1] and application as basic materials for optoelectronic devices working in the blue and ultraviolet spectral region [2][3][4]. In particular GaN and AlN can withstand high temperatures and have large piezoelectric constants which makes them suitable for applications in highfrequency devices, sensors and low-dimensional structures [5,6].Although basic information about group-III nitrides e.g. crystal-and band structure have been available for a decade several details still remained unclear. In the following review of our work we present results of first-and second-order Raman investigations on various GaN, AlN, and Al x Ga 1-x N samples and point out some remarkable details of the structural and optical properties of these materials.

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Determination of the Al mole fraction and the band gap bowing of epitaxial AlxGa1−xN films

Cited by 304 publications

References 23 publications

AlGaN-Based Bragg Reflectors

AlGaN-Based Bragg Reflectors

Bending in HVPE GaN free‐standing films: effects of laser lift‐off, polishing and high‐pressure annealing

Lattice dynamics in GaN and AlN probed with first‐ and second‐order Raman spectroscopy

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