Effects of Polarization in Optoelectronic Quantum Structures

Butté, R.; Grandjean, N.

doi:10.1007/978-0-387-68319-5_9

Cited by 26 publications

(15 citation statements)

References 129 publications

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“…For a SQW structure with unstrained barriers the piezoelectric polarization in the barriers is zero, and the electric field in the quantum well due to polarization is given by [21] (2) where and are the spontaneous polarizations in the barriers and QW, respectively, is the piezoelectric polarization in the QW, and is the dielectric constant in the QW. From (2) it is clear that the direction and magnitude of the polarization discontinuity determine the direction and magnitude of the resulting electric field.…”

Section: Polarization In Group Iii-nitridesmentioning

confidence: 99%

Semipolar $({\hbox{20}}\bar{{\hbox{2}}}\bar{{\hbox{1}}})$ InGaN/GaN Light-Emitting Diodes for High-Efficiency Solid-State Lighting

Feezell

Speck

DenBaars

et al. 2013

J. Display Technol.

324

155

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This work examines the effects of polarization-related electric fields on the energy band diagrams, wavelength shift, wave function overlap, and efficiency droop for InGaN quantum wells on various crystal orientations, including polar (0001) ( -plane), semipolar 2021 , semipolar 2021 , and nonpolar 1010 ( -plane). Based on simulations, we show that the semipolar 2021 orientation exhibits excellent potential for the development of high-efficiency, low-droop light-emitting diodes (LEDs). We then present recent advancements in crystal growth, optical performance, and thermal performance of semipolar 2021 LEDs. Finally, we demonstrate a low-droop, high-efficiency single-quantum-well blue semipolar 2021 LED with an external quantum efficiency of more than 50% at 100 A/cm .

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Section: Polarization In Group Iii-nitridesmentioning

confidence: 99%

Semipolar $({\hbox{20}}\bar{{\hbox{2}}}\bar{{\hbox{1}}})$ InGaN/GaN Light-Emitting Diodes for High-Efficiency Solid-State Lighting

Feezell

Speck

DenBaars

et al. 2013

J. Display Technol.

324

155

View full text Add to dashboard Cite

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“…A small arbitrary value 10 3 V/cm was used in this calculation as the barrier electric field, since we assume that the polarization-induced electric field in the thick barriers is much weaker than in the thin QW. 4 Actually, it was found that the exciton parameters only weakly depend on the barrier electric field in a wide range between zero and 10 4 V/cm. According to the performed calculations, the exciton energy matching the position of the experimentally observed PL peak is obtained provided that the QW intrinsic electric field is as high as 7 Â 10 5 V/cm.…”

Section: The Quantum Confined Stark Effect and Exciton Localizationmentioning

confidence: 99%

“…According to the performed calculations, the exciton energy matching the position of the experimentally observed PL peak is obtained provided that the QW intrinsic electric field is as high as 7 Â 10 5 V/cm. One should note that the estimation of the intrinsic electric field in this pyroelectric structure, performed in the simplest model of an undoped QW, 4 provides a comparable value 7:5 Â 10 5 V/cm. The respective calculated radiative lifetime of excitons was 15 ns.…”

Section: The Quantum Confined Stark Effect and Exciton Localizationmentioning

confidence: 99%

“…The emission efficiency can be enhanced by decreasing the QW width below $3 nm that partly suppresses the QCSE. 4 On the other hand the possibility of using thicker QWs with deeper electron and hole levels could be especially advantageous in order to overcome the effect of efficiency droop in high-power LEDs.…”

Section: Introductionmentioning

confidence: 99%

“…4 Another disadvantage of the Alrich AlGaN heterostructures is the phenomenon of switching the polarization of the emitted light from transverse electric (TE) polarization to transverse magnetic (TM) polarization as the Al content increases. 5 The origin of this effect is the crossover of heavy-hole and split-off-hole bands in AlGaN at a certain Al composition.…”

Section: Introductionmentioning

confidence: 99%

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Suppression of the quantum-confined Stark effect in AlxGa1−xN/AlyGa1−yN corrugated quantum wells

Торопов

Shevchenko

Shubina

et al. 2013

Journal of Applied Physics

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We report comparative studies of 6-nm-thick Al x Ga 1Àx N/Al y Ga 1Ày N pyroelectric quantum wells (QWs) grown by plasma-assisted molecular beam epitaxy on c-sapphire substrates with a thick AlN buffer deposited under different growth conditions. The Al-rich growth conditions result in a 2D growth mode and formation of a planar QW, whereas the N-rich conditions lead to a 3D growth mode and formation of a QW corrugated on the size scale of 200-300 nm. Time-resolved photoluminescence (PL) measurements reveal a strong quantum-confined Stark effect in the planar QW, manifested by a long PL lifetime and a red shift of the PL line. In the corrugated QW, the emission line emerges 200 meV higher in energy, the low-temperature PL lifetime is 40 times shorter, and the PL intensity is stronger ($4 times at 4.5 K and $60 times at 300 K). The improved emission properties are explained by suppression of the quantum-confined Stark effect due to the reduction of the built-in electric field within the QW planes, which are not normal to the [0001] direction, enhanced carrier localization, and improved efficiency of light extraction. V C 2013 AIP Publishing LLC.[http://dx

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Avoiding the Center‐Symmetry Trap: Programmed Assembly of Dipolar Precursors into Porous, Crystalline Molecular Thin Films

et al. 2021

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Liquid‐phase, quasi‐epitaxial growth is used to stack asymmetric, dipolar organic compounds on inorganic substrates, permitting porous, crystalline molecular materials that lack inversion symmetry. This allows material fabrication with built‐in electric fields. A new programmed assembly strategy based on metal–organic frameworks (MOFs) is described that facilitates crystalline, noncentrosymmetric space groups for achiral compounds. Electric fields are integrated into crystalline, porous thin films with an orientation normal to the substrate. Changes in electrostatic potential are detected via core‐level shifts of marker atoms on the MOF thin films and agree with theoretical results. The integration of built‐in electric fields into organic, crystalline, and porous materials creates possibilities for band structure engineering to control the alignment of electronic levels in organic molecules. Built‐in electric fields may also be used to tune the transfer of charges from donors loaded via programmed assembly into MOF pores. Applications include organic electronics, photonics, and nonlinear optics, since the absence of inversion symmetry results in a clear second‐harmonic generation signal.

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Effects of Polarization in Optoelectronic Quantum Structures

Cited by 26 publications

References 129 publications

Semipolar $({\hbox{20}}\bar{{\hbox{2}}}\bar{{\hbox{1}}})$ InGaN/GaN Light-Emitting Diodes for High-Efficiency Solid-State Lighting

Semipolar $({\hbox{20}}\bar{{\hbox{2}}}\bar{{\hbox{1}}})$ InGaN/GaN Light-Emitting Diodes for High-Efficiency Solid-State Lighting

Suppression of the quantum-confined Stark effect in AlxGa1−xN/AlyGa1−yN corrugated quantum wells

Avoiding the Center‐Symmetry Trap: Programmed Assembly of Dipolar Precursors into Porous, Crystalline Molecular Thin Films

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