Electronic properties of axial In $$_x$$ x Ga $$_{1-x}$$ 1 - x N insertions in GaN nanowires

Marquardt, Oliver; Geelhaar, Lutz; Brandt, O.

doi:10.1007/s10825-015-0669-1

Cited by 4 publications

(10 citation statements)

References 23 publications

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“…Mi et al demonstrated high-power InGaN/GaN/AlGaN core–shell NW-LEDs with output powers up to ∼1.5 mW for emission at ∼630 nm measured in pulse mode . The optical power achieved in this investigation is considerably higher than previous reports on long-wavelength NW-LEDs or planar LEDs despite the high In composition that reduces the overlap of electron–hole wave functions (see the Supporting Information for the Nextnano simulation of the band diagram of red LEDs, S2) …”

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confidence: 57%

“…42 The optical power achieved in this investigation is considerably higher than previous reports on long-wavelength NW-LEDs or planar LEDs despite the high In composition that reduces the overlap of electron−hole wave functions (see the Supporting Information for the Nextnano simulation of the band diagram of red LEDs, S2). 43 The inset in Figure 3c shows the measured injection current density versus voltage characteristics of LEDs different sizes. The LEDs with smaller sizes showed lower forward voltages and lower series resistances.…”

Section: Nano Lettersmentioning

confidence: 99%

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Droop-Free, Reliable, and High-Power InGaN/GaN Nanowire Light-Emitting Diodes for Monolithic Metal-Optoelectronics

et al. 2016

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A droop-free nitride light-emitting diode (LED) with the capacity to operate beyond the "green gap" has been a subject of intense scientific and engineering interest. While several properties of nanowires on silicon make them promising for use in LED development, the high aspect ratio of individual nanowires and their laterally discontinuous features limit phonon transport and device performance. Here, we report on the monolithic integration of metal heat-sink and droop-free InGaN/GaN quantum-disks-in-nanowire LEDs emitting at ∼710 nm. The reliable operation of our uncooled nanowire-LEDs (NW-LEDs) epitaxially grown on molybdenum was evident in the constant-current soft burn-in performed on a 380 μm × 380 μm LED. The square LED sustained 600 mA electrical stress over an 8 h period, providing stable light output at maturity without catastrophic failure. The absence of carrier and phonon transport barriers in NW-LEDs was further inferred from current-dependent Raman measurements (up to 700 mA), which revealed the low self-heating. The radiative recombination rates of NW-LEDs between room temperature and 40 °C was not limited by Shockley-Read-Hall recombination, Auger recombination, or carrier leakage mechanisms, thus realizing droop-free operation. The discovery of reliable, droop-free devices constitutes significant progress toward the development of nanowires for practical applications. Our monolithic approach realized a high-performance device that will revolutionize the way high power, low-junction-temperature LED lamps are manufactured for solid-state lighting and for applications in high-temperature harsh environment.

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confidence: 57%

Section: Nano Lettersmentioning

confidence: 99%

Droop-Free, Reliable, and High-Power InGaN/GaN Nanowire Light-Emitting Diodes for Monolithic Metal-Optoelectronics

et al. 2016

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“…[ 36 ] Thus, the strain partitioning and relaxation in an axial NW heterostructure is expected to alter the piezoelectric polarization, associated charge distribution, and in turn internal quantum efficiency. [ 15 , 16 , 37 , 38 ] In general, strain relaxation occurring in the NW heterostructure is known to reduce the piezoelectric field and thus enhance electron–hole overlap and, consequently, the internal quantum efficiency. This relation is very well known and has been addressed in many previous publications.…”

Section: Resultsmentioning

confidence: 99%

“…[ 10 , 11 ] Interestingly, it has been predicted by several theoretical studies that the InGaN QDs induce complex strain and polarization fields. [ 12 , 13 ] This further emphasizes the importance of comprehensive understanding on the correlation of the geometric shape and boundary condition of InGaN QD with the strain (and polarization) fields in InGaN/GaN MQW NW heterostructures.…”

Section: Introductionmentioning

confidence: 99%

High‐Resolution Mapping of Strain Partitioning and Relaxation in InGaN/GaN Nanowire Heterostructures

et al. 2022

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Growing an In x Ga 1− x N/GaN (InGaN/GaN) multi‐quantum well (MQW) heterostructure in nanowire (NW) form is expected to overcome limitations inherent in light‐emitting diodes (LEDs) based on the conventional planar heterostructure. The epitaxial strain induced in InGaN/GaN MQW heterostructure can be relaxed through the sidewalls of NW, which is beneficial to LEDs because a much larger misfit strain with higher indium concentration can be accommodated with reduced piezoelectric polarization fields. The strain relaxation, however, renders highly complex strain distribution within the NW heterostructure. Here the authors show that complementary strain mapping using scanning transmission electron microscopy and dark‐field inline holography can comprehend the strain distribution within the axial In 0.3 Ga 0.7 N/GaN MQW heterostructure embedded in GaN NW by providing the strain maps which can cover the entire NW and fine details near the sidewalls. With the quantitative evaluation by 3D finite element modelling, it is confirmed that the observed complex strain distribution is induced by the strain relaxation leading to the strain partitioning between InGaN quantum disk, GaN quantum well, and the surrounding epitaxial GaN shell. The authors further show that the strain maps provide the strain tensor components which are crucial for accurate assessment of the strain‐induced piezoelectric fields in NW LEDs.

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“…This effect, however, evidently depends on the structural parameters of the nanowire heterostructure in a highly nontrivial manner. In the present study, we have considered the In x Ga 1−x N insertion to be represented by a disk, but it is known from experiment that the insertion may assume rather complex shapes that have been found to affect the spatial distribution of the electron and hole charge densities as well [31]. To predict the transition energy and the electron-hole overlap of a specific nanowire heterostructure would require a complete three-dimensional reconstruction of the insertions's size, shape and composition on a nm scale.…”

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confidence: 99%

Influence of strain relaxation in axial ${\mathrm{In}}_{x}{\mathrm{Ga}}_{1-x}{\rm{N}}/\mathrm{GaN}$ nanowire heterostructures on their electronic properties

Marquardt¹,

Krause²,

Kaganer³

et al. 2017

Nanotechnology

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We present a systematic theoretical study of the influence of elastic strain relaxation on the built-in electrostatic potentials and the electronic properties of axial [Formula: see text] nanowire (NW) heterostructures. Our simulations reveal that for a sufficiently large ratio between the thickness of the [Formula: see text] disk and the diameter of the NW, the elastic relaxation leads to a significant reduction of the built-in electrostatic potential in comparison to a planar system of similar layer thickness and In content. In this case, the ground state transition energies approach constant values with increasing thickness of the disk and only depend on the In content, a behavior usually associated to that of a quantum well free of built-in electrostatic potentials. We show that the structures under consideration are by no means field-free, and the built-in potentials continue to play an important role even for ultrathin NWs. In particular, strain and the resulting polarization potentials induce complex confinement features of electrons and holes, which depend on the In content, shape, and dimensions of the heterostructure.

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Electronic properties of axial In $$_x$$ x Ga $$_{1-x}$$ 1 - x N insertions in GaN nanowires

Cited by 4 publications

References 23 publications

Droop-Free, Reliable, and High-Power InGaN/GaN Nanowire Light-Emitting Diodes for Monolithic Metal-Optoelectronics

Droop-Free, Reliable, and High-Power InGaN/GaN Nanowire Light-Emitting Diodes for Monolithic Metal-Optoelectronics

High‐Resolution Mapping of Strain Partitioning and Relaxation in InGaN/GaN Nanowire Heterostructures

Influence of strain relaxation in axial ${\mathrm{In}}_{x}{\mathrm{Ga}}_{1-x}{\rm{N}}/\mathrm{GaN}$ nanowire heterostructures on their electronic properties

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