Band-edge photoluminescence and reflectivity of nonpolar<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mo>(</mml:mo><mml:mn>11</mml:mn><mml:mover accent="true"><mml:mn>2</mml:mn><mml:mo stretchy="false">¯</mml:mo></mml:mover><mml:mn>0</mml:mn><mml:mo>)</mml:mo></mml:mrow></mml:math>and semipolar<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mo>(</mml:mo><mml:mn>11</mml:mn><mml:mover accent="true"><mml:mn>2</mml:mn><mml:mo s

Gühne, T.; Bougrioua, Z.; Laugt, S.; Némoz, M.; Vennéguès, P.; Vinter, B.; Leroux, M.

doi:10.1103/physrevb.77.075308

Cited by 33 publications

(32 citation statements)

References 36 publications

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“…Secondly, the in-plane anisotropic strain and differences in the hole effective masses along the growth direction can lead to lifting of the valence band degeneracy that enables the emission of strong linearly polarised light from nonpolar InGaN QW structures. 32,33 Clearly, the presence or absence of the macroscopic intrinsic electric field will impact mainly on the radiative recombination rate but there is a stark contrast between not only the time scale of the recombination dynamics 34 but also the more basic radiative recombination processes 35 for nonpolar and polar InGaN QW structures.…”

Section: à2mentioning

confidence: 99%

The nature of carrier localisation in polar and nonpolar InGaN/GaN quantum wells

Dawson

Schulz²,

Oliver

et al. 2016

Journal of Applied Physics

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In this paper, we compare and contrast the experimental data and the theoretical predictions of the low temperature optical properties of polar and nonpolar InGaN/GaN quantum well structures. In both types of structure, the optical properties at low temperatures are governed by the effects of carrier localisation. In polar structures, the effect of the in-built electric field leads to electrons being mainly localised at well width fluctuations, whereas holes are localised at regions within the quantum wells, where the random In distribution leads to local minima in potential energy. This leads to a system of independently localised electrons and holes. In nonpolar quantum wells, the nature of the hole localisation is essentially the same as the polar case but the electrons are now coulombically bound to the holes forming localised excitons. These localisation mechanisms are compatible with the large photoluminescence linewidths of the polar and nonpolar quantum wells as well as the different time scales and form of the radiative recombination decay curves.

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Section: à2mentioning

confidence: 99%

The nature of carrier localisation in polar and nonpolar InGaN/GaN quantum wells

Dawson

Schulz²,

Oliver

et al. 2016

Journal of Applied Physics

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“…Also the intrinsic field leads to a spatial separation of electron and hole wave functions, causing a reduced radiative recombination rate [4,6], an effect that can be particularly undesirable for high-efficiency optoelectronic devices. To circumvent these effects arising from the intrinsic built-in fields, which fundamentally are caused by the growth along the polar c axis, significant research has been directed towards the fabrication of semi-and nonpolar structures [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. In the case of semi-and nonpolar planes the c axis is at a nonvanishing angle with respect to the growth direction.…”

Section: Introductionmentioning

confidence: 99%

“…Consequently, in such a structure the radiative recombination rate should be much higher than in polar QW structures. Additionally, (In,Ga)N QWs grown on nonpolar planes offer the possibility of acting as highly efficient sources of linearly polarized light [11,12,19], which may be of practical use in, e.g., back-lit liquid crystal displays [12]. The potentially high degree of optical linear polarization (DOLP) in a nonpolar QW originates mainly from differences in the effective hole masses along the growth direction, which leads to a lifting of the degeneracy of the highest lying p-like valence bands [19,22].…”

Section: Introductionmentioning

confidence: 99%

Structural, electronic, and optical properties ofm-plane InGaN/GaN quantum wells: Insights from experiment and atomistic theory

Schulz¹,

Tanner

O’Reilly

et al. 2015

Phys. Rev. B

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In this paper we present a detailed analysis of the structural, electronic, and optical properties of an m-plane (In,Ga)N/GaN quantum well structure grown by metal organic vapor phase epitaxy. The sample has been structurally characterized by x-ray diffraction, scanning transmission electron microscopy, and 3D atom probe tomography. The optical properties of the sample have been studied by photoluminescence (PL), time-resolved PL spectroscopy, and polarized PL excitation spectroscopy. The PL spectrum consisted of a very broad PL line with a high degree of optical linear polarization. To understand the optical properties we have performed atomistic tight-binding calculations, and based on our initial atom probe tomography data, the model includes the effects of strain and built-in field variations arising from random alloy fluctuations. Furthermore, we included Coulomb effects in the calculations. Our microscopic theoretical description reveals strong hole wave function localization effects due to random alloy fluctuations, resulting in strong variations in ground state energies and consequently the corresponding transition energies. This is consistent with the experimentally observed broad PL peak. Furthermore, when including Coulomb contributions in the calculations we find strong exciton localization effects which explain the form of the PL decay transients. Additionally, the theoretical results confirm the experimentally observed high degree of optical linear polarization. Overall, the theoretical data are in very good agreement with the experimental findings, highlighting the strong impact of the microscopic alloy structure on the optoelectronic properties of these systems.

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“…[8][9][10][11] Luminescence properties of a-plane GaN, including temperature and polarization dependent, spatially resolved photoluminescence ͑PL͒ and cathodoluminescence, were also particularly studied. [12][13][14] Recently, the authors reported the splitting and anisotropy of emission light polarization of the m-plane GaN on LAO͑100͒ by using PL measurements. 15 In this letter, we investigate the polarization-angle and temperature dependence of the polarized PL transitions of the m-plane GaN film on LAO͑100͒ in order to explore the evolution of splitting valence band under anisotropic strain conditions.…”

mentioning

confidence: 99%

“…Two nonradiative channels are included for the best fitting as suggested. 12,14 The thermal quenching of the NBE peak is obtained with activation energies E 1 ϳ 6.3Ϯ 0.8 meV and E 2 ϳ 16.6Ϯ 3.2 meV. The first nonradiative process with thermal activation energy E 1 in the low-temperature range ͑Ͻ35 K͒ is attributed to the hole delocalization, and the second process with E 2 at higher temperatures is due to the electron delocalization.…”

mentioning

confidence: 99%

Polarization and temperature dependence of photoluminescence of m-plane GaN grown on γ-LiAlO2 (100) substrate

Liu

Kong

Zhang

et al. 2009

Applied Physics Letters

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We investigated the polarization and temperature dependence of photoluminescence ͑PL͒ of m-plane GaN grown on ␥-LiAlO 2 ͑100͒ substrate. The calculated electronic band structure with k • p Hamiltonian points out the energy splitting as well as polarization selection originate from the m-plane GaN epilayer under anisotropic strain. The polarization-angle dependence PL spectra are found to be selected from in-plane x-and z-polarized emission, corresponding to T 1 and T 2 transition. And the intensity distribution of the fitting peaks satisfies the Malus' law. An S-shape energy evolution of near band edge peak on temperatures is observed, which originates from the transition between the localized holes and electrons in triangular potentials induced by basal stacking faults. © 2009 American Institute of Physics. ͓DOI: 10.1063/1.3204453͔ Spontaneous and piezoelectric polarization along the ͓0001͔ axis of wurtzite GaN and its alloys greatly affect the efficiency of luminescence in GaN-based optoelectronic devices. 1 In order to eliminate these polarization effects, one way is to deposit an m-or a-plane GaN film along unconventional non-polar directions, such as ͓1100͔ ͑Ref. 2-4͒ or ͓1120͔. 5-7 ␥-LiAlO 2 ͑LAO͒ has a tetragonal structure and its ͑100͒ plane exhibits a comparatively small lattice mismatch to GaN ͑1100͒. Since the m-plane GaN was grown by molecular-beam epitaxy on this substrate, 2 the development of nonpolar GaN based optoelectronic devices has attracted much attention. Unlike c-plane GaN, nonpolar GaN usually suffers from anisotropic in-plane strain, which leads to a splitting in the electronic band structure ͑EBS͒. Therefore, understanding the EBS of nonpolar GaN is significant for the application of optoelectronic devices. Previously, optical measurements, such as reflectance, transmission, and photoreflectance, were used to determine the EBS near the ⌫ point and verify the theoretical calculation of the energy splitting of the m-plane GaN. [8][9][10][11] Luminescence properties of a-plane GaN, including temperature and polarization dependent, spatially resolved photoluminescence ͑PL͒ and cathodoluminescence, were also particularly studied. [12][13][14] Recently, the authors reported the splitting and anisotropy of emission light polarization of the m-plane GaN on LAO͑100͒ by using PL measurements. 15 In this letter, we investigate the polarization-angle and temperature dependence of the polarized PL transitions of the m-plane GaN film on LAO͑100͒ in order to explore the evolution of splitting valence band under anisotropic strain conditions.The studied sample of a typical 0.92 m thick m-plane GaN with background electron concentration ϳ2 ϫ 10 18 cm −3 ͑named as sample I͒ was grown on LAO͑100͒ by metalorganic chemical vapor deposition. 4 High-resolution x-ray diffraction technique revealed the m-plane GaN epilayer under biaxial compressive strain of xx = −0.79% and zz = −0.14% with an out-of-plane dilatation yy = 0.38%. 15 An unintentionally doped n-type c-plane GaN with thickness of 2.5 m on ␣-Al 2 O...

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Band-edge photoluminescence and reflectivity of nonpolar(112¯0)and semipolar(112

Cited by 33 publications

References 36 publications

The nature of carrier localisation in polar and nonpolar InGaN/GaN quantum wells

The nature of carrier localisation in polar and nonpolar InGaN/GaN quantum wells

Structural, electronic, and optical properties ofm-plane InGaN/GaN quantum wells: Insights from experiment and atomistic theory

Polarization and temperature dependence of photoluminescence of m-plane GaN grown on γ-LiAlO2 (100) substrate

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