Prospective emission efficiency and in-plane light polarization of nonpolar m-plane InxGa1−xN∕GaN blue light emitting diodes fabricated on freestanding GaN substrates

Koyama, Takahiro; Onuma, Takeyoshi; Masui, Hisashi; Chakraborty, Arpan; Haskell, B. A.; Keller, S.; Mishra, U. K.; Speck, James S.; Nakamura, Shuji; DenBaars, Steven P.; Sota, Takayuki; Chichibu, S. F.

doi:10.1063/1.2337085

Cited by 74 publications

(58 citation statements)

References 30 publications

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“…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.…”

mentioning

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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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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“…For common GaN LED structures grown along the c axis, access to this polarized light can only be gained by measurements taken from the edge of the sample [19][20]. Several authors have reported polarized light emission for LED structures grown on nonpolar or semipolar GaN substrates [21][22]. In the present study, we investigate the approach employing photonic crystals (PhCs) which do not require the growth on different orientation of sapphire or GaN substrates nor using specific wafer orientations.…”

Section: Polarized Light Emission Properties Of Gan-based Photonic Crmentioning

confidence: 99%

Anisotropy of Light Extraction Emission with High Polarization Ratio from GaN-based Photonic Crystal Light-Emitting Diodes

Lai¹,

Chao²,

Kuo³

2010

Recent Optical and Photonic Technologies

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“…It originates from the built-in electric fields along the [0001] direction separate the electron and hole wave functions in a quantum well (QW) thereby reducing the recombination probability of electron-hole pairs. In order to eliminate these polarization effects, one alternative way is to grow non-polar, e.g., (the a-plane) GaN thin films and InGaN/GaN QWs along unconventional non-c-axis directions 2,3 .…”

Section: Introductionmentioning

confidence: 99%

“…The m-plane InGaN/GaN multiple quantum wells (MQWs) have been synthesized substrates by molecular-beam epitaxy(MBE) 4 and LED structures have been grown by metal-organic chemical vapor deposition (MOCVD) on LiAlO 2 [LAO] (100) 5,6 , recently. This non-polar plane GaN will exhibit intrinsic in-plane anisotropy even in the unstrained case due to the broken hexagonal symmetry.…”

Section: Introductionmentioning

confidence: 99%

Non-polar m-plane GaN film and polarized InGaN/GaN LED grown on LiAlO 2 (001) substrates

et al. 2010

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The non-polar m-plane GaN film and polarized InGaN/GaN light-emitting diode (LED) grown by metal-organic chemical vapor deposition (MOCVD) on LiAlO 2 (100) substrates were investigated. Firstly, the simulation of excitonic transition energies and polarization effects on band structure of non-polar plane GaN was studied using the k· p Hamiltonian approach. Due to small lattice mismatch between GaN and LiAlO 2 substrate, X-ray diffraction (XRD) revealed that the obtained m-plane GaN film has only ] 00 1 1 [ orientation with single-crystalline quality. In addition, anisotropic crystallographic properties and strain were found, which originates from the broken hexagonal symmetry. The anisotropic strain further separates the energy levels of top valence band at Γ point. The energy splitting as 37meV as well as in-plane polarization anisotropy for transitions are found by the polarized photoluminescence spectra at room temperature, which is consistent with our simulation. The fabricated InGaN/GaN LED on LiAlO 2 (100) emits green polarized light at room temperature. And the polarization degree of the emission reaches up to 60% at the wavelength of 520nm.

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Prospective emission efficiency and in-plane light polarization of nonpolar m-plane InxGa1−xN∕GaN blue light emitting diodes fabricated on freestanding GaN substrates

Cited by 74 publications

References 30 publications

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

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

Anisotropy of Light Extraction Emission with High Polarization Ratio from GaN-based Photonic Crystal Light-Emitting Diodes

Non-polar m-plane GaN film and polarized InGaN/GaN LED grown on LiAlO 2 (001) substrates

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