All metalorganic chemical vapor phase epitaxy of p/n-GaN tunnel junction for blue light emitting diode applications

Neugebauer, Silvio; Hoffmann, Marc P.; Witte, Hartmut; Bläsing, J.; Dadgar, A.; Strittmatter, A.; Niermann, Tore; Narodovitch, Michael; Lehmann, Michael

doi:10.1063/1.4978268

Cited by 67 publications

(62 citation statements)

References 30 publications

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“…This heavy Ge doping in GaN and AlGaN contributes to an increase in surface roughness, in this case of 2.5nm and 1.9nm respectively. Also, we observe the formation of V-pits in the surfaces of both the Gedoped layers related to the decoration of threading dislocations 20,34 . These pits are thicker and deeper for the the GaN TJ (average thickness of 100nm and depth of 30nm) than for the AlGaN TJ (average thickness of 52nm and depth of 2nm).…”

Section: Resultsmentioning

confidence: 81%

“…Germanium n-doped GaN tunnel junctions on top of visible GaN LEDs were already demonstrated by Neugebauer et al 20 using an all-MOCVD growth approachnonetheless, this growth method is not optimal for tunnel junctions due to the re-passivation of the Mg acceptors by the H present in the growth chamber. A post-growth annealing to reactivate these acceptors would then be necessary, 21 but the p-doped layers in TJ devices are always buried under a highly n-doped layer, hindering the diffusion of H. [22][23][24] Additionally, for Ge-doped AlGaN layers, the Ge activation energy increases with the concentration of Al, 25 which yields a new challenge.…”

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confidence: 99%

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Ge doped GaN and Al0.5Ga0.5N-based tunnel junctions on top of visible and UV light emitting diodes

Arcara

Damilano

Feuillet

et al. 2019

Journal of Applied Physics

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The use of tunnel junctions (TJs) is a potential solution in blue LEDs to poor p-contacts, replacing it by another n-contact. TJs are even more advantageous for UV emitting structures, which suffer from the considerably low injection efficiency in high Al concentration UV LEDs. In this work we report our work on Ge n-doped GaN and AlGaN TJs grown on top of blue and UV LEDs, respectively, by a hybrid growth. We have achieved state of the art mobility (67cm 2 /V.s) and resistivity (1.7x10 -4 Ω.cm) at a free electron concentration of 5.5x10 20 cm -3 in Ge-doped GaN. With an emission wavelength of 436nm, the GaN TJ slightly increased the optical power of the blue LED. The AlGaN TJs, on the other hand, improved the optical power of the UV LED (304nm) by at least a factor of 3, suggesting the enhancement of the hole injection efficiency by the use of TJs in UV emitting structures.

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Section: Resultsmentioning

confidence: 81%

mentioning

confidence: 99%

Ge doped GaN and Al0.5Ga0.5N-based tunnel junctions on top of visible and UV light emitting diodes

Arcara

Damilano

Feuillet

et al. 2019

Journal of Applied Physics

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“…The other proposal to enable the efficient hole injection from the p-type ohmic contact into the hole supplier is to utilize a tunnel junction [ 56 , 57 , 58 ]. The advantage of the tunnel junction is a direct contact between the n + -GaN layer and the metal, since the n + -GaN layer has a much higher doping efficiency than the p + -GaN layer.…”

Section: Increase the Hole Injection Efficiency From The P-type Ohmentioning

confidence: 99%

On the Hole Injection for III-Nitride Based Deep Ultraviolet Light-Emitting Diodes

Zhang

et al. 2017

Materials

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The hole injection is one of the bottlenecks that strongly hinder the quantum efficiency and the optical power for deep ultraviolet light-emitting diodes (DUV LEDs) with the emission wavelength smaller than 360 nm. The hole injection efficiency for DUV LEDs is co-affected by the p-type ohmic contact, the p-type hole injection layer, the p-type electron blocking layer and the multiple quantum wells. In this report, we review a large diversity of advances that are currently adopted to increase the hole injection efficiency for DUV LEDs. Moreover, by disclosing the underlying device physics, the design strategies that we can follow have also been suggested to improve the hole injection for DUV LEDs.

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“…The depletion width of the tunnel junction was measured to be 9 nm using off‐axis electron holography, which agreed well with the simulated value of 10.7 nm. The nonabrupt p–n tunnel junction required optimization of the doping profiles and higher doping levels across the junction region …”

Section: The Off‐axis Electron Holography Schemementioning

confidence: 99%

Electron Holographic Study of Semiconductor Light‐Emitting Diodes

Gao

2017

Small

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Semiconductor light-emitting diodes (LEDs), especially GaN-based heterostructures, are widely used in light illumination. The lack of inversion symmetry of wurtzite crystal structures and the lattice mismatch at heterointerfaces cause large polarization fields with contributions from both spontaneous polarization and piezoelectric polarization, which in turn results in obvious quantum confined stark effect. It is possible to alleviate this effect if the local electrostatic fields and band alignment induced charge redistribution can be quantitatively determined across the heterostructures. In this Concept, the applications of electron holography to investigate semiconductor LEDs are summarized. Following the off-axis electron holography scheme, the GaN-based LED heterostructures including InGaN/GaN-based quantum wells, other GaN-based quantum wells, and other forms of GaN-based LED materials are discussed, focusing on the local potential drops, polarization fields, and charge distributions. Moreover, GaAs-based LED heterostructures are briefly discussed. The in-line electron holography scheme emphasizes the capability of large area strain mapping across LED heterostructures with high spatial resolution and accuracy, which is combined with quantitative electrostatic measurements and other advanced transmission electron microscopy characterizations to provide an overall nanometer scale perspective of LED devices for further improvement in their electric and optical properties.

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All metalorganic chemical vapor phase epitaxy of p/n-GaN tunnel junction for blue light emitting diode applications

Cited by 67 publications

References 30 publications

Ge doped GaN and Al0.5Ga0.5N-based tunnel junctions on top of visible and UV light emitting diodes

Ge doped GaN and Al0.5Ga0.5N-based tunnel junctions on top of visible and UV light emitting diodes

On the Hole Injection for III-Nitride Based Deep Ultraviolet Light-Emitting Diodes

Electron Holographic Study of Semiconductor Light‐Emitting Diodes

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