Anisotropic strain and phonon deformation potentials in GaN

Darakchieva, Vanya; Paskova, T.; Schubert, M.; Arwin, Hans; Paskov, Plamen; Ḿonemar, B.; Hommel, D.; Heuken, M.; Off, J.; Scholz, F.; Haskell, B. A.; Fini, P.; Speck, James S.; Nakamura, Shuji

doi:10.1103/physrevb.75.195217

Cited by 102 publications

(88 citation statements)

References 45 publications

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“…28 These nucleation layers serve as templates for the growth of the nonpolar wurtzite film with unique epitaxial relationship with respect to the substrate. 21 On the other hand, the semipolar film is grown directly on the substrate without any nitridation ͑Table I͒. It has been previously shown that direct growth of InN on r-plane sapphire results in the nucleation of zinc-blende InN due to the much lower lattice mismatch compared to the wurtzite InN.…”

Section: Semipolar "101 1… Innmentioning

confidence: 99%

“…20 The structural anisotropy of nonpolar III-nitride films affects their optical performance and device-relevant characteristics ͑carrier mobility, degradation, etc.͒, which requires detailed study of these issues. While the structural anisotropy of nonpolar GaN films have been extensively studied 1, [14][15][16][17][21][22][23] the information on the structural characteristics of nonpolar InN is very scarce 24,25 and detailed reports exists only for films grown on GaN substrates. 26,27 However, the nonpolar GaN substrates are not only extremely expensive but also have a limited supply.…”

Section: Introductionmentioning

confidence: 99%

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Structural anisotropy of nonpolar and semipolar InN epitaxial layers

Darakchieva

Xie

Franco

et al. 2010

Journal of Applied Physics

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We present a detailed study of the structural characteristics of molecular beam epitaxy grown nonpolar InN films with a-and m-plane surface orientations on r-plane sapphire and ͑100͒ ␥-LiAlO 2 , respectively, and semipolar ͑1011͒ InN grown on r-plane sapphire. The on-axis rocking curve ͑RC͒ widths were found to exhibit anisotropic dependence on the azimuth angle with minima at InN ͓0001͔ for the a-plane films, and maxima at InN ͓0001͔ for the m-plane and semipolar films. The different contributions to the RC broadening are analyzed and discussed. The finite size of the crystallites and extended defects are suggested to be the dominant factors determining the RC anisotropy in a-plane InN, while surface roughness and curvature could not play a major role. Furthermore, strategy to reduce the anisotropy and magnitude of the tilt and minimize defect densities in a-plane InN films is suggested. In contrast to the nonpolar films, the semipolar InN was found to contain two domains nucleating on zinc-blende InN͑111͒A and InN͑111͒B faces. These two wurtzite domains develop with different growth rates, which was suggested to be a consequence of their different polarity. Both, a-and m-plane InN films have basal stacking fault densities similar or even lower compared to nonpolar InN grown on free-standing GaN substrates, indicating good prospects of heteroepitaxy on foreign substrates for the growth of InN-based devices.

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Section: Semipolar "101 1… Innmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Structural anisotropy of nonpolar and semipolar InN epitaxial layers

Darakchieva

Xie

Franco

et al. 2010

Journal of Applied Physics

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“…40,41 The uncoupled phonon mode parameters and the high-frequency limit of the dielectric function of GaN and InN are taken from our previous works. 40,42,43 The FCC contribution with consideration of longitudinal optical phonon plasmon coupling (LPP) was described by applying the Kukharskii model 29,44 e kð?Þ ðxÞ ¼ e 1;kð?…”

Section: Experimental and Data Analysismentioning

confidence: 99%

Effect of Mg doping on the structural and free-charge carrier properties of InN films

Xie¹,

Sédrine²,

Schöche³

et al. 2014

Journal of Applied Physics

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We present a comprehensive study of free-charge carrier and structural properties of two sets of InN films grown by molecular beam epitaxy and systematically doped with Mg from 1.0 Â 10 18 cm À3 to 3.9 Â 10 21 cm À3 . The free electron and hole concentration, mobility, and plasmon broadening parameters are determined by infrared spectroscopic ellipsometry. The lattice parameters, microstructure, and surface morphology are determined by high-resolution X-ray diffraction and atomic force microscopy. Consistent results on the free-charge carrier type are found in the two sets of InN films and it is inferred that p-type conductivity could be achieved for 1.0 Â 10 18 cm À3 Շ [Mg] Շ 9.0 Â 10 19 cm À3 . The systematic change of free-charge carrier properties with Mg concentration is discussed in relation to the evolution of extended defect density and growth mode. A comparison between the structural characteristics and free electron concentrations in the films provides insights in the role of extended and point defects for the n-type conductivity in InN. It further allows to suggest pathways for achieving compensated InN material with relatively high electron mobility and low defect densities. The critical values of Mg concentration for which polarity inversion and formation of zinc-blende InN occurred are determined. Finally, the effect of Mg doping on the lattice parameters is established and different contributions to the strain in the films are discussed. V C 2014 AIP Publishing LLC.

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“…It can be easily implemented to work with uniaxial materials [45] (like corundum) and is sensitive to small anisotropies [46,47]. For our sample geometry, in which an oblique angle of incidence was used, only the ordinary dielectric function can be accessed with high sensitivity.…”

Section: Introductionmentioning

confidence: 99%

Ordinary dielectric function of corundumlike α−Ga2O3 from 40 meV to 20 eV

Feneberg

Nixdorf

Neumann

et al. 2018

Phys. Rev. Materials

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The linear optical response of metastable α-Ga 2 O 3 is investigated by spectroscopic ellipsometry. We determine the ordinary dielectric function from lattice vibrations up to the vacuum ultraviolet spectral range at room temperature for a sample with a (0001) surface. Three out of four E u infrared-active phonon modes are unambiguously determined, and their frequencies are in good agreement with density functional theory calculations. The dispersion of the refractive index in the visible and ultraviolet part of the spectrum is determined. High-energy interband transitions are characterized up to 20 eV. By comparison with the optical response of α-Al 2 O 3 and with theoretical results, a tentative assignment of interband transitions is proposed.

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Anisotropic strain and phonon deformation potentials in GaN

Cited by 102 publications

References 45 publications

Structural anisotropy of nonpolar and semipolar InN epitaxial layers

Structural anisotropy of nonpolar and semipolar InN epitaxial layers

Effect of Mg doping on the structural and free-charge carrier properties of InN films

Ordinary dielectric function of corundumlike α−Ga2O3 from 40 meV to 20 eV

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