Growth of M-plane GaN(100) on γ-LiAlO

Waltereit, Patrick; Brandt, O.; Ramsteiner, M.; Uecker, R.; Reiche, P.; Ploog, K.

doi:10.1016/s0022-0248(00)00605-9

Cited by 137 publications

(90 citation statements)

References 11 publications

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“…While the beneficial and deleterious aspects of the presence of these polarization discontinuities have been, until recently, understood within the context of ͑0001͒ oriented films, 1,2 which have historically dominated the literature and commercial applications of the wurtzite group-III nitrides, there has been a large body of recent work on removing and perhaps engineering polarization discontinuities via the growth of nonpolar and semipolar orientations of GaN. [3][4][5] Growth on inclined facets tilts the polarization toward the plane of the growth surface, thereby reducing the magnitude of the component of the polarization parallel to the growth direction. In the limiting case of a-plane ͑1120͒ and m-plane ͑1010͒ orientations, the polarization axis is placed entirely in the plane of the growth surface, and polarization discontinuities at heterointerfaces are not possible.…”

Section: Introductionmentioning

confidence: 99%

Growth of p-type and n-type m-plane GaN by molecular beam epitaxy

McLaurin

Mates

et al. 2006

Journal of Applied Physics

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Plasma-assisted molecular beam epitaxial growth of Mg-doped, p-type and Si-doped, n-type m-plane GaN on 6H m-plane SiC is demonstrated. Phase-pure, m-plane GaN films exhibiting a large anisotropy in film mosaic ͑ϳ0.2°full width at half maximum, x-ray rocking curve scan taken parallel to ͓1120͔ versus ϳ2°parallel to ͓0001͔͒ were grown on m-plane SiC substrates. Maximum hole concentrations of ϳ7 ϫ 10 18 cm −3 were achieved with p-type conductivities as high as ϳ5 ⍀ −1 cm −1 without the presence of Mg-rich inclusions or inversion domains as viewed by cross-section transmission electron microscopy. Temperature dependent Hall effect measurements indicate that the Mg-related acceptor state in m-plane GaN is the same as that exhibited in c-plane GaN. Free electron concentrations as high as ϳ4 ϫ 10 18 cm −3 were measured in the Si-doped m-plane GaN with corresponding mobilities of ϳ500 cm 2 / V s measured parallel to the ͓1120͔ direction.

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Section: Introductionmentioning

confidence: 99%

Growth of p-type and n-type m-plane GaN by molecular beam epitaxy

McLaurin

Mates

et al. 2006

Journal of Applied Physics

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“…The lattice mismatches along the x and z directions are ͓0001͔ GaN ʈ ͓010͔ LAO ϳ −0.3% and ͓1120͔ GaN ʈ ͓001͔ LAO ϳ −1.7%. 16 The thermalexpansion coefficient mismatches along the x and z directions are −67% and −69%. 19 Thus, it is reasonably considered that the anisotropic strain ratio primarily originates from lattice mismatch ratio along the x and z directions.…”

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confidence: 97%

“…4 Both anisotropic crystallography and surface morphology are quite similar to the behavior of nonpolar GaN grown on different substrates. 5,8,16 This result implies different mosaic block dimensions along the two orthogonal directions, parallel and perpendicular to the ͓0001͔ direction of m-plane GaN. In order to obtain the tilt and lateral correlation length of mosaic blocks along the two directions, W-H plots of the ͑1100͒, ͑2200͒, and ͑3300͒ -scan diffraction peak widths are implemented.…”

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confidence: 99%

Anisotropic crystallographic properties, strain, and their effects on band structure of m-plane GaN on LiAlO2(100)

Liu

Zhang

Xie

et al. 2008

Applied Physics Letters

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The m-plane GaN films grown on LiAlO 2 ͑100͒ by metal-organic chemical vapor deposition exhibit anisotropic crystallographic properties. The Williamson-Hall plots point out they are due to the different tilts and lateral correlation lengths of mosaic blocks parallel and perpendicular to GaN͓0001͔ in the growth plane. The symmetric and asymmetric reciprocal space maps reveal the strain of m-plane GaN to be biaxial in-plane compress xx = −0.79% and zz = −0.14% with an out-of-plane dilatation yy = 0.38%. This anisotropic strain further separates the energy levels of top valence band at ⌫ point. The energy splitting as 37 meV as well as in-plane polarization anisotropy for transitions are found by the polarized photoluminescence spectra at room temperature. © 2008 American Institute of Physics. ͓DOI: 10.1063/1.2951618͔The wurtzite structure of III-nitrides leads to electrostatic fields along the ͓0001͔ direction due to spontaneous and piezoelectric polarization, when the film is grown on c-oriented substrates. 1 These built-in electric fields along the ͓0001͔ direction separate the electron and hole wave functions in a quantum well ͑QW͒ thereby reducing the recombination probability of electron-hole pairs. Consequently, it results in reduction of quantum efficiency of light-emitting diodes. 2 A way to overcome this deficiency is to grow GaNbased QWs along nonpolar orientations, for example, m plane 3,4 or a plane. 5,6 It has been shown that the electric field can be avoided in such nitride QWs. When ͓1100͔ or ͓1120͔ becomes the growth direction, the c axis of GaN lattice lies down in the growth plane. As a consequence, the C 6v hexagonal symmetry of the c growth plane is reduced to C 2v symmetry of the m growth plane. Firstly, it would show the anisotropic crystallographic characteristics. 7,8 Secondly, the nonpolar GaN films experience strong anisotropic deformation due to different in-plane lattice mismatches and thermalexpansion coefficients between GaN and underlying substrates. In the case of c-plane GaN films, isotropic strain in the c-plane preserves C 6v symmetry in the x-y plane so that no significant in-plane physical anisotropy occurs. The situation is quite different for nonpolar GaN films. Anisotropic in-plane strain components further lift the symmetry in the growth plane, which significantly modify the top three valence band ͑VB͒ states at ⌫ point. 9,10 Both the energy splitting and polarization selection of the transitions between conduction band ͑CB͒ and VB have been observed by absorption, reflectance, and photoreflectance spectroscopy. 11,12 Recently, transmission anisotropy spectroscopy has been utilized to obtain the energy splitting and polarization information of m-plane GaN films. 13 Although the in-plane strain components are important for the modifications in band structure of nonpolar GaN, it is still difficult to experimentally determine the full state of strain. In the case of m plane, GaN films are grown along GaN ͓1100͔ direction. The growth plane is the x-z plane, and the growth direc...

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“…1, 2 In an effort to eliminate the effects of internal polarization-induced electric fields, wurtzite group III nitride films have been grown in the a-plane ͑1120͒ and m-plane ͑1010͒ orientations. 3,4 These growth directions orient the polarization in the plane of heterointerface and, thus, there are no polarization-related electric fields in laterally uniform devices. Plasma-assisted molecular-beam epitaxy ͑PAMBE͒-grown c-face GaN suffers from a second deleterious effect in that doping with the commonly used acceptor Mg at high concentrations or low III/V ratios often results in the formation of inversion domains that degrade the quality of the crystal.…”

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Molecular-beam epitaxy of p-type m-plane GaN

McLaurin

Mates

Speck

2005

Applied Physics Letters

139

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We report on the plasma-assisted molecular-beam epitaxy of Mg-doped ͑1010͒ GaN on ͑1010͒ 6H-SiC. Secondary ion mass spectroscopy measurements show the incorporation of Mg into the GaN films with an enhanced Mg incorporation under N-rich conditions relative to Ga-rich growth. Transport measurements of Mg-doped layers grown under Ga-rich conditions show hole concentrations in the range of p =1ϫ 10 18 to p =7ϫ 10 18 cm −3 and a dependence between hole concentration and Mg beam equivalent pressure. An anisotropy in in-plane hole mobilities was observed, with the hole mobility parallel to ͓1120͔ being higher than that parallel to ͓0001͔ for the same hole concentration. Mobilities parallel to ͓1120͔ were as high as ϳ11.5 cm 2 /Vs ͑at p ϳ 1.8 ϫ 10 18 cm −3 ͒.

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Growth of M-plane GaN(100) on γ-LiAlO

Cited by 137 publications

References 11 publications

Growth of p-type and n-type m-plane GaN by molecular beam epitaxy

Growth of p-type and n-type m-plane GaN by molecular beam epitaxy

Anisotropic crystallographic properties, strain, and their effects on band structure of m-plane GaN on LiAlO2(100)

Molecular-beam epitaxy of p-type m-plane GaN

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