Seeded growth of AlN on N- and Al-polar AlN seeds by physical vapor transport

Herro, Ziad; Zhuang, D.; Schlesser, R.; Collazo, Ramón; Sitar, Zlatko

doi:10.1016/j.jcrysgro.2005.10.074

Cited by 84 publications

(68 citation statements)

References 16 publications

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“…[4][5][6][7] These applications in turn triggered improvements in the growth of high-quality AlN, [8][9][10] only recently allowing us to investigate the fundamental properties of this semiconductor in unpreceded quality. For example, the full width at half maximum of donor bound-exciton recombinations in AlN could be shown to be below 500 μeV, allowing for unambiguous identification of these lines, 11,12 or the optical properties of nonpolar quantum wells in AlN barriers could be understood.…”

Section: Introductionmentioning

confidence: 99%

Anisotropic absorption and emission of bulk(11¯00)AlN

et al. 2013

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The intrinsic anisotropic optical properties of wurtzite AlN are investigated in absorption and emission. Full access to the anisotropy of the optical response of the hexagonal material is obtained by investigating the (1100) plane of a high-quality bulk crystal allowing electric field E polarization perpendicular (E ⊥ c) and parallel (E c) to the optical axis c. Spectroscopic ellipsometry yields the ordinary (ε ⊥ ) and extraordinary (ε ) dielectric functions (DFs) from 0.58 up to 20 eV. The comparison of the experimental data with recently calculated DFs demonstrates that Coulomb interaction has a strong impact not only on the spectral dependence around the fundamental absorption edge but also on the high-energy features usually discussed in terms of van Hove singularities. The fits of the second-order derivatives of ε and ε ⊥ provide the transition energies for the main features in this range. The DFs close to the fundamental absorption edge, dominated by free excitons, exciton-phonon complexes, and the exciton continuum, are independently confirmed by reflectivity and synchrotron-based photoluminescence excitation studies. Values for the band gaps, the crystal field ( cf = −221 ± 2 meV), and spin-orbit splittings ( so = 13 ± 2 meV) are obtained. Furthermore, we obtain accurate values for the static dielectric constants of ε S⊥ = 7.65 and ε S = 9.21, entering, e.g., the calculations of exciton binding energies. Photoluminescence is used to investigate the emission properties of the same sample.

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Section: Introductionmentioning

confidence: 99%

Anisotropic absorption and emission of bulk(11¯00)AlN

et al. 2013

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“…This specimen shape particularly suitable for uniaxial pressure measurements was cut from AlN single crystal wafer material grown by the physical vapor transport method on N-polar c-plane (0001) seeds [25][26][27]. Polar sample surfaces were polished to an optical finish in order to facilitate a homogenous strain distribution throughout the sample after application of uniaxial stress onto the corresponding c-plane surfaces.…”

Section: Methodsmentioning

confidence: 99%

“…[22] for the hydrostatic PPCs due to the employment of high quality bulk AlN crystals. Such bulk AlN well represents most recent crystal growth advances [25,26,33] and even allows the reproducible application of hydrostatic pressures in excess of 20 GPa [22]. Hence, in order to further compare the obtained PDPs a and b with literature values (Tab.…”

Section: Raman Spectroscopy Undermentioning

confidence: 99%

Phonon pressure coefficients and deformation potentials of wurtzite AlN determined by uniaxial pressure-dependent Raman measurements

et al. 2014

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We studied bulk crystals of wurtzite AlN by means of uniaxial pressure-dependent Raman measurements. As a result, we derive the phonon pressure coefficients and deformation potentials for all zone center optical phonon modes. For the A1 and E1 modes we further experimentally determined the uniaxial pressure dependence of their longitudinal optical -transverse optical (LO-TO) splittings. Our experimental approach delivers new insight into the large variance among previously reported phonon deformation potentials, which are predominantly based on heteroepitaxial growth of AlN and the ball-on-ring technique. Additionally, the measured phonon pressure coefficients are compared to their theoretical counterparts obtained by density functional theory implemented in the SIESTA package. Generally, we observe a good agreement between the calculated and measured phonon pressure coefficients but some particular Raman modes exhibit significant discrepancies similar to the case of wurtzite GaN and ZnO, clearly motivating the presented uniaxial pressure-dependent Raman measurements on bulk AlN crystals.

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“…Although there are still challenges, such as contamination from impurities, lack of large-sized AlN seeds, and difficulty in tailoring desired thermal profile inside the growth reactor that hinder reproducible growth to cite a few [37], several groups have achieved PVT-grown AlN single crystals with diameters up to 2 inch [35,[38][39][40][41][42]. X-ray rocking curves with a full width at half maximum (FWHM) close to 30 arcsec for both (0002) and (1012) reflections and etch pit densities (EPDs) below 10 4 cm −2 were reported with an usable area of~85% [35].…”

Section: Growth and Optical Properties Of Bulk Aln For Duv Ledsmentioning

confidence: 99%

Status of Growth of Group III-Nitride Heterostructures for Deep Ultraviolet Light-Emitting Diodes

et al. 2017

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Abstract:We overview recent progress in growth aspects of group III-nitride heterostructures for deep ultraviolet (DUV) light-emitting diodes (LEDs), with particular emphasis on the growth approaches for attaining high-quality AlN and high Al-molar fraction AlGaN. The discussion commences with the introduction of the current status of group III-nitride DUV LEDs and the remaining challenges. This segues into discussion of LED designs enabling high device performance followed by the review of advances in the methods for the growth of bulk single crystal AlN intended as a native substrate together with a discussion of its UV transparency. It should be stated, however, that due to the high-cost of bulk AlN substrates at the time of writing, the growth of DUV LEDs on foreign substrates such as sapphire still dominates the field. On the deposition front, the heteroepitaxial growth approaches incorporate high-temperature metal organic chemical vapor deposition (MOCVD) and pulsed-flow growth, a variant of MOCVD, with the overarching goal of enhancing adatom surface mobility, and thus epitaxial lateral overgrowth which culminates in minimization the effect of lattice-and thermal-mismatches. This is followed by addressing the benefits of pseudomorphic growth of strained high Al-molar fraction AlGaN on AlN. Finally, methods utilized to enhance both p-and n-type conductivity of high Al-molar fraction AlGaN are reviewed.

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Seeded growth of AlN on N- and Al-polar AlN seeds by physical vapor transport

Cited by 84 publications

References 16 publications

Anisotropic absorption and emission of bulk(11¯00)AlN

Anisotropic absorption and emission of bulk(11¯00)AlN

Phonon pressure coefficients and deformation potentials of wurtzite AlN determined by uniaxial pressure-dependent Raman measurements

Status of Growth of Group III-Nitride Heterostructures for Deep Ultraviolet Light-Emitting Diodes

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