Quantitative determination of hexagonal minority phase in cubic GaN using Raman spectroscopy

Siegle, H.; Eckey, L.; Hoffmann, A.; Thomsen, C.; Meyer, B. K.; Schikora, D.; Hankeln, M.; Lischka, K.

doi:10.1016/0038-1098(95)00561-7

Cited by 150 publications

(59 citation statements)

References 13 publications

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“…Since the c-GaN layer is transparent for the excitation laser beam, a measurable TO signal arises from the forward-scattering component induced by the laser beam that is reflected at the GaN/substrate interface [23]. As can be seen in Fig.…”

Section: Raman Spectra Of C-ganmentioning

confidence: 86%

Anharmonic phonon decay in cubic GaN

et al. 2015

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We present a Raman-scattering study of optical phonons in zinc-blende (cubic) GaN for temperatures ranging from 80 to 750 K. The experiments were performed on high-quality, cubic GaN films grown by molecular-beam epitaxy 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 longitudinal-optical (LO) mode relaxation is found to occur via asymmetric decay into acoustic phonons, with an appreciable contribution of higher-order processes. The transverse-optical 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 found.

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Section: Raman Spectra Of C-ganmentioning

confidence: 86%

Anharmonic phonon decay in cubic GaN

et al. 2015

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“…Raman spectroscopy is able to verify the purity of GaN layers with respect to polytype-domain formation [59]. The different polarization scattering selection rules allow us to distinguish between the two phases by selecting appropriate scattering geometries.…”

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

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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“…Polarization dependent Raman measurements [11] as well as reciprocal space maps [12] are used to study the phase purity. Under optimized conditions a phase purity better than 99.9% is demonstrated for cubic GaN epilayers [13].…”

Section: Undoped Cubic Group Iii-nitritesmentioning

confidence: 99%