Polarization effects in photoluminescence of C- and M-plane GaN/AlGaN multiple quantum wells

Kuokštis, E.; Chen, C. Q.; Gaevski, Mikhail; Sun, Wenhong; Yang, Jinwei; Simin, Grigory; Khan, M. Asif; Maruska, H. P.; Hill, David W.; Chou, M. C.; Gallagher, John J.; Chai, B. H. T.

doi:10.1063/1.1524298

Cited by 111 publications

(69 citation statements)

References 11 publications

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“…Screening of the electric field reduces the QCSE, reducing the red-shift. [19,26,65,66,67]. The absence of new emission peaks or significant broadening in Fig.…”

Section: Iiia Emission Energy To Emission Rate Relationmentioning

confidence: 99%

Nanometer-scale monitoring of quantum-confined Stark effect and emission efficiency droop in multiple GaN/AlN quantum disks in nanowires

et al. 2016

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We report on a detailed study of the intensity dependent optical properties of individual GaN/AlN Quantum Disks (QDisks) embedded into GaN nanowires (NW). The structural and optical properties of the QDisks were probed by high spatial resolution cathodoluminescence (CL) in a scanning transmission electron microscope (STEM). By exciting the QDisks with a nanometric electron beam at currents spanning over 3 orders of magnitude, strong non-linearities (energy shifts) in the light emission are observed. In particular, we find that the amount of energy shift depends on the emission rate and on the QDisk morphology (size, position along the NW and shell thickness). For thick QDisks (>4nm), the QDisk emission energy is observed to blue-shift with the increase of the emission intensity. This is interpreted as a consequence of the increase of carriers density excited by the incident electron beam inside the QDisks, which screens the internal electric field and thus reduces the quantum confined Stark effect (QCSE) present in these QDisks. For thinner QDisks (<3 nm), the blue-shift is almost absent in agreement with the negligible QCSE at such sizes. For QDisks of intermediate sizes there exists a current threshold above which the energy shifts, marking the transition from unscreened to partially screened QCSE. From the threshold value we estimate the lifetime in the unscreened regime. These observations suggest that, counterintuitively, electrons of high energy can behave ultimately as single electron-hole pair generators. In addition, when we increase the current from 1 pA to 10 pA the light emission efficiency drops by more than one order of magnitude. This reduction of the emission efficiency is a manifestation of the 'efficiency droop' as observed in nitride-based 2D light emitting diodes, a phenomenon tentatively attributed to the Auger effect. *

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“…Screening of the electric field reduces the QCSE, reducing the red-shift. [19,26,65,66,67]. The absence of new emission peaks or significant broadening in Fig.…”

Section: Iiia Emission Energy To Emission Rate Relationmentioning

confidence: 99%

Nanometer-scale monitoring of quantum-confined Stark effect and emission efficiency droop in multiple GaN/AlN quantum disks in nanowires

et al. 2016

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“…This is caused by the electrostatic fields ͑F pol ͒ parallel to the QW normal due to the spontaneous and piezoelectric polarizations. [2][3][4][5] Distinct from polar c-plane QWs, those grown in nonpolar orientations such as a-plane ͑1120͒ and m-plane ͑1100͒ do not suffer from QCSEs, [6][7][8][9][10][11] because the polar c-axis lies in the QW plane. Accordingly, high int can be expected for nonpolar LEDs 12,13 even when highly strained QWs are contained.…”

mentioning

confidence: 99%

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

Onuma

Masui

et al. 2006

Applied Physics Letters

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Prospective equivalent internal quantum efficiency ͑ int ͒ of approximately 34% at 300 K was demonstrated for the blue emission peak of nonpolar m-plane ͑1100͒ In x Ga 1−x N / GaN multiple quantum well light emitting diodes ͑LEDs͒ fabricated on freestanding m-plane GaN substrates. Although the int value is yet lower than that of conventional c-plane blue LEDs ͑Ͼ70% ͒, the results encourage one to realize high performance green, amber, and red LEDs by reducing the concentration of nonradiative defects, according to the absence of the quantum-confined Stark effects due to the polarization fields parallel to the quantum well normal. The electric field component of the blue surface emission was polarized perpendicular to the c axis with the in-plane polarization ratio of 0.58 at 300 K.

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“…[1 100] or [1120] , for the growth direction. Recently, there have been several approaches to realize nonpolar GaN, M-plane films [1] and M-plane heterostructures [2,3] on γ-LiAlO 2 (100) , M-plane heterostructures on M-plane GaN templates [4], as well as A-plane films [5] and A-plane heterostructures [6 -8] on R-plane sapphire. The coordinate system used for the investigation of the polarization properties is…”

Section: Introductionmentioning

confidence: 99%

Polarization properties of nonpolar GaN films and (In,Ga)N/GaN multiple quantum wells

Grahn

2004

Physica Status Solidi (b)

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We have realized nonpolar GaN films and (In,Ga)N/GaN multiple quantum wells (MQWs) by plasmaassisted molecular-beam epitaxy on γ-LiAlO 2 (100) substrates. The GaN films and (In,Ga)N/GaN MQWs are grown in an M-plane configuration, i.e., the c-axis of the wurtzite unit cell lies in the growth plane. For compressively and anisotropically strained M-plane GaN films, the band structure of the valence band changes in such a way that the optical transmittance becomes 100% linearly polarized for two orthogonal in-plane directions, where one of these directions is parallel to the c-axis of the GaN film. Within a certain energy range, the M-plane GaN film thereby acts as a polarization filter. The photoluminescence spectra of M-plane In 0.1 Ga 0.9 N/GaN MQWs exhibit a strong in-plane optical anisotropy for linear polarization with an energy-dependent polarization degree of up to 96%, which is presumably also due to a large valence-band splitting induced by the large compressive strain in the QWs.

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Polarization effects in photoluminescence of C- and M-plane GaN/AlGaN multiple quantum wells

Cited by 111 publications

References 11 publications

Nanometer-scale monitoring of quantum-confined Stark effect and emission efficiency droop in multiple GaN/AlN quantum disks in nanowires

Nanometer-scale monitoring of quantum-confined Stark effect and emission efficiency droop in multiple GaN/AlN quantum disks in nanowires

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

Polarization properties of nonpolar GaN films and (In,Ga)N/GaN multiple quantum wells

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