Up to fifth-order Raman scattering of InP under nonresonant conditions

We present Raman spectra of InP measured under nonresonant conditions revealing multiphonon processes up to fifth order. Using an incident photon energy in the absorption region of the compound but far from any of its interband transitions, nonresonant multiphonon processes of order higher than two, which have not been reported so far in a zinc-blende-type semiconductor, have been observed in indium phosphide. In this way it has been possible to detect contributions not only from the longitudinal optical phonons but also from the transverse optical phonons in the higher-order peaks. We find a very good agreement between multiples of the TO- and LO-phonon frequencies at the zone center and the higher-order phonons measured in the experiments. The trend of strong intensity reductions observed when passing from first to second as well as from second to third order is not maintained when going from third to fourth, and from fourth to fifth order

Spectrally and spatially resolved cathodoluminescence of undoped/Mg-doped GaN core-shell nanowires: a local probe into activation of Mg acceptors in non-polar and semi-polar crystal faces

Producción CientíficaSpectrally and spatially resolved cathodoluminescence (CL) measurements were carried out at 80 K on undoped/Mg-doped GaN core-shell nanowires grown by selective area growth metalorganic vapor phase epitaxy in order to investigate locally the optical activity of the Mg dopants. A study of the luminescence emission distribution over the different regions of the nanowires is presented. We have investigated the CL fingerprints of the Mg incorporation into the non-polar lateral prismatic facets and the semi-polar facets of the pyramidal tips. The amount of Mg incorporation/activation was varied by using several Mg/Ga flow ratios and post-growth annealing treatments. For lower Mg/Ga flow ratios, the annealed nanowires clearly display a donor-acceptor pair band emission peaking at 3.26-3.27 eV and up to 4 LO phonon replicas, which can be considered as a reliable indicator of effective p-type Mg doping in the nanowire shell. For higher Mg/Ga flow ratios, a substantial enhancement of the yellow luminescence emission as well as several emission subbands are observed, which suggests an increase of disorder and the presence of defects as a consequence of the excess Mg doping,Junta de Castilla y León (programa de apoyo a proyectos de investigación – Ref. VA302U13

Anharmonic phonon decay in cubic GaN

We present a Raman scattering study of optical phonons in zincblende (cubic) GaN for temperatures ranging from 80 to 750 K. The experiments were performed on high quality, cubic GaN films grown by molecular beamepitaxy on GaAs (001) substrates. The observed temperature dependence of the optical phonon frequencies and linewidths is analyzed in the framework of anharmonic decay theory, and possible decay channels are discussed in the light of density-functional theory calculations. The LO mode relaxation is found to occur via asymmetric decay into acoustic phonons, with an appreciable contribution of higher order processes. The TO mode linewidth shows a weak temperature dependence and its frequency downshift is primarily determined by the lattice thermal expansion. The LO phonon lifetime is derived from the observed Raman linewidth and an excellent agreement with previous theoretical predictions is foun

Comparison of Raman-scattering and Shubnikov-de Haas measurements to determine charge density in doped semiconductors

We have verified the accuracy of free-charge determinations from Raman scattering in doped semiconductors by comparing the results obtained from phonon-plasmon coupled-mode line-shape fits with the charge-density values extracted from the analysis of the Shubnikov-de Haas oscillations. The experiments were carried out on n-InP layers, and conduction band nonparabolicity was included both in the Lindhard-Mermin model used to fit the Raman spectra and in the Shubnikov-de Haas analysis. We find a very good agreement between Raman and magnetotransport results, which confirms the reliability of the charge-density determination from Raman-scattering measurements when the line-shape analysis is carried out using the Lindhard-Mermin model

Overtones of interlayer shear modes in the phonon-assisted emission spectrum of hexagonal boron nitride

We address the intrinsic optical properties of hexagonal boron nitride in deep ultraviolet. We show that the fine structure of the phonon replicas arises from overtones involving up to six low-energy interlayer shear modes. These lattice vibrations are specific to layered compounds since they correspond to the shear rigid motion between adjacent layers, with a characteristic energy of about 6-7 meV. We obtain a quantitative interpretation of the multiplet observed in each phonon replica under the assumption of a cumulative Gaussian broadening as a function of the overtone index, and with a phenomenological line broadening taken identical for all phonon types. We show from our quantitative interpretation of the full emission spectrum above 5.7 eV that the energy of the involved phonon mode is 6.8±0.5 meV, in excellent agreement with temperature-dependent Raman measurements of the low-energy interlayer shear mode in hexagonal boron nitride. We highlight the unusual properties of this material where the optical response is tailored by the phonon group velocities in the middle of the Brillouin zone. © 2017 American Physical Society.Peer reviewe

High-pressure optical absorption in InN: Electron density dependence in the wurtzite phase and reevaluation of the indirect band gap of rocksalt InN

We report on high-pressure optical absorption measurements on InN epilayers with a range of free-electron concentrations (5×1017–1.6×1019 cm−3) to investigate the effect of free carriers on the pressure coefficient of the optical band gap of wurtzite InN. With increasing carrier concentration, we observe a decrease of the absolute value of the optical band gap pressure coefficient of wurtzite InN. An analysis of our data based on the k·p model allows us to obtain a pressure coefficient of 32 meV/GPa for the fundamental band gap of intrinsic wurtzite InN. Optical absorption measurements on a 5.7-μm-thick InN epilayer at pressures above the wurtzite-to-rocksalt transition have allowed us to obtain an accurate determination of the indirect band gap energy of rocksalt InN as a function of pressure. Around the phase transition (∼15 GPa), a band gap value of 0.7 eV and a pressure coefficient of ∼23 meV/GPa are obtained. ©2012 American Physical SocietyThis work was supported by the Spanish Ministry of Science and Innovation through Project No. MAT2010-16116.Ibáñez, J.; Segura, A.; García-Domene, B.; Oliva, R.; Manjón Herrera, FJ.; Yamaguchi, T.; Nanishi, Y.... (2012). High-pressure optical absorption in InN: Electron density dependence in the wurtzite phase and reevaluation of the indirect band gap of rocksalt InN. Physical Review B. 86:35210-1-35210-5. https://doi.org/10.1103/PhysRevB.86.035210S35210-135210-586Wu, J. (2009). When group-III nitrides go infrared: New properties and perspectives. Journal of Applied Physics, 106(1), 011101. doi:10.1063/1.3155798Ueno, M., Yoshida, M., Onodera, A., Shimomura, O., & Takemura, K. (1994). Stability of the wurtzite-type structure under high pressure: GaN and InN. Physical Review B, 49(1), 14-21. doi:10.1103/physrevb.49.14Uehara, S., Masamoto, T., Onodera, A., Ueno, M., Shimomura, O., & Takemura, K. (1997). Equation of state of the rocksalt phase of III–V nitrides to 72 GPa or higher. Journal of Physics and Chemistry of Solids, 58(12), 2093-2099. doi:10.1016/s0022-3697(97)00150-9Pinquier, C., Demangeot, F., Frandon, J., Chervin, J.-C., Polian, A., Couzinet, B., … Maleyre, B. (2006). Raman scattering study of wurtzite and rocksalt InN under high pressure. Physical Review B, 73(11). doi:10.1103/physrevb.73.115211Ibáñez, J., Manjón, F. J., Segura, A., Oliva, R., Cuscó, R., Vilaplana, R., … Artús, L. (2011). High-pressure Raman scattering in wurtzite indium nitride. Applied Physics Letters, 99(1), 011908. doi:10.1063/1.3609327Li, S. X., Wu, J., Haller, E. E., Walukiewicz, W., Shan, W., Lu, H., & Schaff, W. J. (2003). Hydrostatic pressure dependence of the fundamental bandgap of InN and In-rich group III nitride alloys. Applied Physics Letters, 83(24), 4963-4965. doi:10.1063/1.1633681Franssen, G., Gorczyca, I., Suski, T., Kamińska, A., Pereiro, J., Muñoz, E., … Svane, A. (2008). Bowing of the band gap pressure coefficient in InxGa1−xN alloys. Journal of Applied Physics, 103(3), 033514. doi:10.1063/1.2837072Kamińska, A., Franssen, G., Suski, T., Gorczyca, I., Christensen, N. E., Svane, A., … Georgakilas, A. (2007). Role of conduction-band filling in the dependence of InN photoluminescence on hydrostatic pressure. Physical Review B, 76(7). doi:10.1103/physrevb.76.075203Shan, W., Walukiewicz, W., Haller, E. E., Little, B. D., Song, J. J., McCluskey, M. D., … Stall, R. A. (1998). Optical properties of InxGa1−xN alloys grown by metalorganic chemical vapor deposition. Journal of Applied Physics, 84(8), 4452-4458. doi:10.1063/1.368669Millot, M., Geballe, Z. M., Yu, K. M., Walukiewicz, W., & Jeanloz, R. (2012). Red-green luminescence in indium gallium nitride alloys investigated by high pressure optical spectroscopy. Applied Physics Letters, 100(16), 162103. doi:10.1063/1.4704367Franssen, G., Suski, T., Perlin, P., Teisseyre, H., Khachapuridze, A., Dmowski, L. H., … Schaff, W. (2006). Band-to-band character of photoluminescence from InN and In-rich InGaN revealed by hydrostatic pressure studies. Applied Physics Letters, 89(12), 121915. doi:10.1063/1.2356994Ibáñez, J., Segura, A., Manjón, F. J., Artús, L., Yamaguchi, T., & Nanishi, Y. (2010). Electronic structure of wurtzite and rocksalt InN investigated by optical absorption under hydrostatic pressure. Applied Physics Letters, 96(20), 201903. doi:10.1063/1.3431291Cuscó, R., Ibáñez, J., Alarcón-Lladó, E., Artús, L., Yamaguchi, T., & Nanishi, Y. (2009). Raman scattering study of the long-wavelength longitudinal-optical-phonon–plasmon coupled modes in high-mobility InN layers. Physical Review B, 79(15). doi:10.1103/physrevb.79.155210Cuscó, R., Alarcón-Lladó, E., Ibáñez, J., Yamaguchi, T., Nanishi, Y., & Artús, L. (2009). Raman scattering study of background electron density in InN: a hydrodynamical approach to the LO-phonon–plasmon coupled modes. Journal of Physics: Condensed Matter, 21(41), 415801. doi:10.1088/0953-8984/21/41/415801Syassen, K. (2008). Ruby under pressure. High Pressure Research, 28(2), 75-126. doi:10.1080/08957950802235640Wu, J., Walukiewicz, W., Shan, W., Yu, K. M., Ager, J. W., Li, S. X., … Schaff, W. J. (2003). Temperature dependence of the fundamental band gap of InN. Journal of Applied Physics, 94(7), 4457-4460. doi:10.1063/1.1605815Wu, J., Walukiewicz, W., Li, S. X., Armitage, R., Ho, J. C., Weber, E. R., … Jakiela, R. (2004). Effects of electron concentration on the optical absorption edge of InN. Applied Physics Letters, 84(15), 2805-2807. doi:10.1063/1.1704853Wu, J., Walukiewicz, W., Shan, W., Yu, K. M., Ager, J. W., Haller, E. E., … Schaff, W. J. (2002). Effects of the narrow band gap on the properties of InN. Physical Review B, 66(20). doi:10.1103/physrevb.66.201403Rinke, P., Winkelnkemper, M., Qteish, A., Bimberg, D., Neugebauer, J., & Scheffler, M. (2008). Consistent set of band parameters for the group-III nitrides AlN, GaN, and InN. Physical Review B, 77(7). doi:10.1103/physrevb.77.075202Furthmüller, J., Hahn, P. H., Fuchs, F., & Bechstedt, F. (2005). Band structures and optical spectra of InN polymorphs: Influence of quasiparticle and excitonic effects. Physical Review B, 72(20). doi:10.1103/physrevb.72.205106Serrano, J., Rubio, A., Hernández, E., Muñoz, A., & Mujica, A. (2000). Theoretical study of the relative stability of structural phases in group-III nitrides at high pressures. Physical Review B, 62(24), 16612-16623. doi:10.1103/physrevb.62.16612Christensen, N. E., & Gorczyca, I. (1994). Optical and structural properties of III-V nitrides under pressure. Physical Review B, 50(7), 4397-4415. doi:10.1103/physrevb.50.4397Duan, M.-Y., He, L., Xu, M., Xu, M.-Y., Xu, S., & Ostrikov, K. (Ken). (2010). Structural, electronic, and optical properties of wurtzite and rocksalt InN under pressure. Physical Review B, 81(3). doi:10.1103/physrevb.81.03310

CoII and CuII Fluorescent Complexes with Acridine-Based Ligands

The condensation reaction of salicylaldehyde or 2‐hydroxynaphthaldehyde with a diamino organic group (Acridine Yellow or diaminoacridine) resulted in the Schiff‐base ligands ACRI‐1, ACRI‐2 and ACRI‐3, with the last two hitherto unknown. Fluorescent ACRI‐1, ACRI‐2 and ACRI‐3 were designed to provide iminophenolic binding pockets for two transition metals and ferromagnetic exchange between the metals. Following our report on the complex [Co2(ACRI‐1)2] (1Co), we report herein the reactions of ACRI‐1, ACRI‐2 and ACRI‐3 with CoII and CuII salts, which afforded the new fluorescent complexes [Cu2(ACRI‐1)2] (1Cu), [Co2(ACRI‐2)2] (2Co), [Cu2(ACRI‐2)2] (2Cu), [Co2(ACRI‐3)2(H2O)4] (3Co) and [Cu2(ACRI‐3)2] (3Cu)

High-pressure lattice dynamics in wurtzite and rocksalt indium nitride investigated by means of Raman spectroscopy

We present an experimental and theoretical lattice-dynamical study of InN at high hydrostatic pressures. We perform Raman scattering measurements on five InN epilayers, with different residual strain and free electron concentrations. The experimental results are analyzed in terms of ab initio lattice-dynamical calculations on both wurtzite InN (w-InN) and rocksalt InN (rs-InN) as a function of pressure. Experimental and theoretical pressure coefficients of the optical modes in w-InN are compared, and the role of residual strain on the measured pressure coefficients is analyzed. In the case of the LO band, we analyze and discuss its pressure behavior considering the double-resonance mechanism responsible for the selective excitation of LO phonons with large wave vectors in w-InN. The pressure behavior of the L− coupled mode observed in a heavily doped n-type sample allows us to estimate the pressure dependence of the electron effective mass in w-InN. The results thus obtained are in good agreement with k⋅p theory. The wurtzite-to-rocksalt phase transition on the upstroke cycle and the rocksalt-to-wurtzite backtransition on the downstroke cycle are investigated, and the Raman spectra of both phases are interpreted in terms of DFT lattice-dynamical calculations. ©2013 American Physical SocietyWork was supported by the Spanish Ministerio de Economia y Competitividad through Projects MAT2010-16116, MAT2010-21270-C04-04 and MALTA Consolider Ingenio 2010 (CSD2007-00045).Ibánez, J.; Oliva, R.; Manjón Herrera, FJ.; Segura, A.; Yamaguchi, T.; Nanishi, Y.; Cuscó, R.... (2013). High-pressure lattice dynamics in wurtzite and rocksalt indium nitride investigated by means of Raman spectroscopy. Physical Review B. 88:115202-1-115202-13. https://doi.org/10.1103/PhysRevB.88.115202S115202-1115202-1388Wu, J. (2009). When group-III nitrides go infrared: New properties and perspectives. Journal of Applied Physics, 106(1), 011101. doi:10.1063/1.3155798Pinquier, C., Demangeot, F., Frandon, J., Pomeroy, J. W., Kuball, M., Hubel, H., … Gil, B. (2004). Raman scattering in hexagonal InN under high pressure. Physical Review B, 70(11). doi:10.1103/physrevb.70.113202Pinquier, C., Demangeot, F., Frandon, J., Chervin, J.-C., Polian, A., Couzinet, B., … Maleyre, B. (2006). Raman scattering study of wurtzite and rocksalt InN under high pressure. Physical Review B, 73(11). doi:10.1103/physrevb.73.115211Yao, L. D., Luo, S. D., Shen, X., You, S. J., Yang, L. X., Zhang, S. J., … Xie, S. S. (2010). Structural stability and Raman scattering of InN nanowires under high pressure. Journal of Materials Research, 25(12), 2330-2335. doi:10.1557/jmr.2010.0290Ibáñez, J., Manjón, F. J., Segura, A., Oliva, R., Cuscó, R., Vilaplana, R., … Artús, L. (2011). High-pressure Raman scattering in wurtzite indium nitride. Applied Physics Letters, 99(1), 011908. doi:10.1063/1.3609327Uehara, S., Masamoto, T., Onodera, A., Ueno, M., Shimomura, O., & Takemura, K. (1997). Equation of state of the rocksalt phase of III–V nitrides to 72 GPa or higher. Journal of Physics and Chemistry of Solids, 58(12), 2093-2099. doi:10.1016/s0022-3697(97)00150-9Duan, M.-Y., He, L., Xu, M., Xu, M.-Y., Xu, S., & Ostrikov, K. (Ken). (2010). Structural, electronic, and optical properties of wurtzite and rocksalt InN under pressure. Physical Review B, 81(3). doi:10.1103/physrevb.81.033102Davydov, V. Y., Klochikhin, A. A., Smirnov, A. N., Strashkova, I. Y., Krylov, A. S., Lu, H., … Gwo, S. (2009). Selective excitation ofE1(LO)andA1(LO)phonons with large wave vectors in the Raman spectra of hexagonal InN. Physical Review B, 80(8). doi:10.1103/physrevb.80.081204Cuscó, R., Ibáñez, J., Alarcón-Lladó, E., Artús, L., Yamaguchi, T., & Nanishi, Y. (2009). Raman scattering study of the long-wavelength longitudinal-optical-phonon–plasmon coupled modes in high-mobility InN layers. Physical Review B, 79(15). doi:10.1103/physrevb.79.155210Ernst, S., Goñi, A. R., Syassen, K., & Cardona, M. (1995). LO-Phonon-plasmon modes in n-GaAs and n-InP under pressure. Journal of Physics and Chemistry of Solids, 56(3-4), 567-570. doi:10.1016/0022-3697(94)00242-8Ernst, S., Goñi, A. R., Syassen, K., & Cardona, M. (1996). Plasmon Raman scattering and photoluminescence of heavily dopedn-type InP near the Γ-X crossover. Physical Review B, 53(3), 1287-1293. doi:10.1103/physrevb.53.1287Lin, Y. C., Chiu, C. H., Fan, W. C., Chia, C. H., Yang, S. L., Chuu, D. S., … Chou, W. C. (2007). Raman scattering of longitudinal-optical-phonon-plasmon coupling in Cl-doped ZnSe under high pressure. Journal of Applied Physics, 102(12), 123510. doi:10.1063/1.2826936Gonze, X., Beuken, J.-M., Caracas, R., Detraux, F., Fuchs, M., Rignanese, G.-M., … Allan, D. C. (2002). First-principles computation of material properties: the ABINIT software project. Computational Materials Science, 25(3), 478-492. doi:10.1016/s0927-0256(02)00325-7Goedecker, S., Teter, M., & Hutter, J. (1996). Separable dual-space Gaussian pseudopotentials. Physical Review B, 54(3), 1703-1710. doi:10.1103/physrevb.54.1703Troullier, N., & Martins, J. L. (1991). Efficient pseudopotentials for plane-wave calculations. Physical Review B, 43(3), 1993-2006. doi:10.1103/physrevb.43.1993Wu, M. F., Zhou, S. Q., Vantomme, A., Huang, Y., Wang, H., & Yang, H. (2006). High-precision determination of lattice constants and structural characterization of InN thin films. Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, 24(2), 275-279. doi:10.1116/1.2167970Ueno, M., Yoshida, M., Onodera, A., Shimomura, O., & Takemura, K. (1994). Stability of the wurtzite-type structure under high pressure: GaN and InN. Physical Review B, 49(1), 14-21. doi:10.1103/physrevb.49.14Serrano, J., Bosak, A., Krisch, M., Manjón, F. J., Romero, A. H., Garro, N., … Kuball, M. (2011). InN Thin Film Lattice Dynamics by Grazing Incidence Inelastic X-Ray Scattering. Physical Review Letters, 106(20). doi:10.1103/physrevlett.106.205501Giannozzi, P., de Gironcoli, S., Pavone, P., & Baroni, S. (1991). Ab initiocalculation of phonon dispersions in semiconductors. Physical Review B, 43(9), 7231-7242. doi:10.1103/physrevb.43.7231Gonze, X., & Lee, C. (1997). Dynamical matrices, Born effective charges, dielectric permittivity tensors, and interatomic force constants from density-functional perturbation theory. Physical Review B, 55(16), 10355-10368. doi:10.1103/physrevb.55.10355Weinstein, B. A. (1977). Phonon dispersion of zinc chalcogenides under extreme pressure and the metallic transformation. Solid State Communications, 24(9), 595-598. doi:10.1016/0038-1098(77)90369-6Yakovenko, E. V., Gauthier, M., & Polian, A. (2004). High-pressure behavior of the bond-bending mode of AIN. Journal of Experimental and Theoretical Physics, 98(5), 981-985. doi:10.1134/1.1767565Ibáñez, J., Segura, A., García-Domene, B., Oliva, R., Manjón, F. J., Yamaguchi, T., … Artús, L. (2012). High-pressure optical absorption in InN: Electron density dependence in the wurtzite phase and reevaluation of the indirect band gap of rocksalt InN. Physical Review B, 86(3). doi:10.1103/physrevb.86.035210Serrano, J., Romero, A. H., Manjón, F. J., Lauck, R., Cardona, M., & Rubio, A. (2004). Pressure dependence of the lattice dynamics of ZnO: Anab initioapproach. Physical Review B, 69(9). doi:10.1103/physrevb.69.094306Cuscó, R., Ibáñez, J., Domenech-Amador, N., Artús, L., Zúñiga-Pérez, J., & Muñoz-Sanjosé, V. (2010). Raman scattering of cadmium oxide epilayers grown by metal-organic vapor phase epitaxy. Journal of Applied Physics, 107(6), 063519. doi:10.1063/1.3357377Cuscó, R., Alarcón-Lladó, E., Ibáñez, J., Yamaguchi, T., Nanishi, Y., & Artús, L. (2009). Raman scattering study of background electron density in InN: a hydrodynamical approach to the LO-phonon–plasmon coupled modes. Journal of Physics: Condensed Matter, 21(41), 415801. doi:10.1088/0953-8984/21/41/415801Cuscó, R., Ibáñez, J., Alarcón-Lladó, E., Artús, L., Yamaguchi, T., & Nanishi, Y. (2009). Photoexcited carriers and surface recombination velocity in InN epilayers: A Raman scattering study. Physical Review B, 80(15). doi:10.1103/physrevb.80.155204Wang, X., Che, S.-B., Ishitani, Y., & Yoshikawa, A. (2006). Experimental determination of strain-free Raman frequencies and deformation potentials for the E2 high and A1(LO) modes in hexagonal InN. Applied Physics Letters, 89(17), 171907. doi:10.1063/1.2364884Perlin, P., Jauberthie-Carillon, C., Itie, J. P., San Miguel, A., Grzegory, I., & Polian, A. (1992). Raman scattering and x-ray-absorption spectroscopy in gallium nitride under high pressure. Physical Review B, 45(1), 83-89. doi:10.1103/physrevb.45.83Perlin, P., Suski, T., Ager, J. W., Conti, G., Polian, A., Christensen, N. E., … Haller, E. E. (1999). Transverse effective charge and its pressure dependence in GaN single crystals. Physical Review B, 60(3), 1480-1483. doi:10.1103/physrevb.60.1480Halsall, M. P., Harmer, P., Parbrook, P. J., & Henley, S. J. (2004). Raman scattering and absorption study of the high-pressure wurtzite to rocksalt phase transition of GaN. Physical Review B, 69(23). doi:10.1103/physrevb.69.235207Goñi, A. R., Siegle, H., Syassen, K., Thomsen, C., & Wagner, J.-M. (2001). Effect of pressure on optical phonon modes and transverse effective charges inGaNandAlN. Physical Review B, 64(3). doi:10.1103/physrevb.64.035205Watson, G. H., Daniels, W. B., & Wang, C. S. (1981). Measurements of Raman intensities and pressure dependence of phonon frequencies in sapphire. Journal of Applied Physics, 52(2), 956-958. doi:10.1063/1.328785Manjón, F. J., Errandonea, D., Romero, A. H., Garro, N., Serrano, J., & Kuball, M. (2008). Lattice dynamics of wurtzite and rocksalt AlN under high pressure: Effect of compression on the crystal anisotropy of wurtzite-type semiconductors. Physical Review B, 77(20). doi:10.1103/physrevb.77.205204Domènech-Amador, N., Cuscó, R., Artús, L., Stoica, T., & Calarco, R. (2012). Longer InN phonon lifetimes in nanowires. Nanotechnology, 23(8), 085702. doi:10.1088/0957-4484/23/8/085702Gorczyca, I., Plesiewicz, J., Dmowski, L., Suski, T., Christensen, N. E., Svane, A., … Speck, J. S. (2008). Electronic structure and effective masses of InN under pressure. Journal of Applied Physics, 104(1), 013704. doi:10.1063/1.2953094Cardona, M., & Güntherodt, G. (Eds.). (1984). Light Scattering in Solids IV. Topics in Applied Physics. doi:10.1007/3-540-11942-6Artús, L., Cuscó, R., Ibáñez, J., Blanco, N., & González-Díaz, G. (1999). 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Surface acoustic wave velocity and elastic constants of cubic GaN

We present high-resolution surface Brillouin scattering measurements on cubic GaN layers grown on GaAs substrate. By using a suitable scattering geometry, scattering by surface acoustic waves is recorded for different azimuthal angles, and the surface acoustic wave velocities are determined. A comparison of experimental results with numerical simulations of the azimuthal dependence of the surface wave velocity shows good agreement and allows a consistent set of elastic constants for c-GaN to be determined