Photoluminescence and Raman studies of GaN films grown by MOCVD

Tung, Luong Tien; Lin, Kuei-Huei; Chang, Edward Yi; Huang, Wei; Hsiao, Yu-Lin; Chiang, Chen‐Yu

doi:10.1088/1742-6596/187/1/012021

Cited by 24 publications

(22 citation statements)

References 39 publications

(47 reference statements)

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“…Such a shift can be ascribed to the relaxation of the compressive strain that exists in GaN/sapphire due to their lattice mismatch and different thermal expansion coefficients. 34 During cool down from the growth temperature, sapphire contracts faster than GaN leading to a build-up of compressive stress in the epilayer. The measured E 2h value of 567.1 cm �1 is close to that in strain-free GaN 35 indicating that the nano rods are fully relaxed prior to re-growth, in agreement with earlier findings.…”

Section: E Nanorod Strain Relaxationmentioning

confidence: 99%

Facet recovery and light emission from GaN/InGaN/GaN core-shell structures grown by metal organic vapour phase epitaxy on etched GaN nanorod arrays

Boulbar¹,

Girgel²,

Lewins³

et al. 2013

Journal of Applied Physics

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The use of etched nanorods from a planar template as a growth scaffold for a highly regular GaN/InGaN/GaN core-shell structure is demonstrated. The recovery of m-plane non-polar facets from etched high-aspect-ratio GaN nanorods is studied with and without the introduction of a hydrogen silsesquioxane passivation layer at the bottom of the etched nanorod arrays. This layer successfully prevented c-plane growth between the nanorods, resulting in vertical nanorod sidewalls (∼89.8°) and a more regular height distribution than re-growth on unpassivated nanorods. The height variation on passivated nanorods is solely determined by the uniformity of nanorod diameter, which degrades with increased growth duration. Facet-dependent indium incorporation of GaN/InGaN/GaN core-shell layers regrown onto the etched nanorods is observed by high-resolution cathodoluminescence imaging. Sharp features corresponding to diffracted wave-guide modes in angle-resolved photoluminescence measurements are evidence of the uniformity of the full core-shell structure grown on ordered etched nanorods

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Section: E Nanorod Strain Relaxationmentioning

confidence: 99%

Facet recovery and light emission from GaN/InGaN/GaN core-shell structures grown by metal organic vapour phase epitaxy on etched GaN nanorod arrays

Boulbar¹,

Girgel²,

Lewins³

et al. 2013

Journal of Applied Physics

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“…PL FWHM values of GaN peaks of all investigated samples vary from 10.2 nm to 11.1 nm, which evidences good quality of the deposited material. Red shift of GaN peak of heterostructures deposited on silicon (from 361.6 nm to 363.5 nm) is related to the higher residual tensile stress present in these samples .…”

Section: Resultsmentioning

confidence: 91%

GaN/AlN superlattice high electron mobility transistor heterostructures on GaN/Si(111)

Wośko

Paszkiewicz

Vincze

et al. 2015

Physica Status Solidi (b)

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In this work we report the growth of AlGaN/GaN heterostructures on silicon substrates using quasi AlGaN barrier layer formed by 6×(AlN/GaN) superlattice (SL) stack with nominal Al content of 35%. This is the first attempt of implementation of quasi AlGaN barrier layer in AlGaN/GaN heterostructure, originally proposed by Kawakami, on the Si(111) substrates by metalorganic vapor phase epitaxy (MOVPE) technique. The electrical properties of high‐electron mobility transistors (HEMT) type SL structures and conventional Al0.28Ga0.72N/GaN heterostructures grown on sapphire and silicon substrates were investigated and compared. The obtained results showed deterioration of channel resistivity in the heterostructure with SLs (1430 Ω/sq) in comparison to the alloy Al0.28Ga0.72N/GaN heterostructure (751 Ω/sq). Additional, surface and chemical structure characterizations were done by atomic force microscopy (AFM) and secondary ion mass spectrometry (SIMS) techniques. The roughness parameter Ra, estimated based on AFM scans of investigated structures was between 0.5 and 1 nm. The SIMS depth profiles of the alloy AlGaN and SL quasi AlGaN barrier did not show any significant differences between the samples deposited on sapphire and silicon substrates. The room temperature photoluminescence spectra of HEMT type SL structures revealed peaks corresponding to GaN and AlGaN band transitions, which indicates lack of sharp interfaces between AlN and GaN layers and thus formation of AlGaN transition regions in AlN/GaN SL stack.

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“…17 The peak at 3.33 eV present in the un-etched sample has been observed in the PL spectra of GaN grown on Si, and is often attributed to the donor acceptor pair (DAP) transitions. 18,19 The 20 meV blueshift of the NBE emission of the etched sample indicates partial strain-relaxation due to etching. Such blue-shift in PL has also been observed for etched GaN nanocolumns on Si.…”

Section: Sidewalls (Center Image Inmentioning

confidence: 99%

Large-area GaN n-core/p-shell arrays fabricated using top-down etching and selective epitaxial overgrowth

Krylyuk

Paramanik

King

et al. 2012

Applied Physics Letters

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We present large-area, vertically aligned GaN n-core and p-shell structures on silicon substrates. The GaN pillars were formed by inductively coupled plasma etching of lithographically patterned n-GaN epitaxial layer. Mg-doped p-GaN shells were formed using selective overgrowth by halide vapor phase epitaxy. The diameter of the cores ranged from 250 nm to 10 lm with varying pitch. The p-shells formed truncated hexagonal pyramids with {1 101} side-facets. Room-temperature photoluminescence and Raman scattering measurements indicate strain-relaxation in the etched pillars and shells. Cross-sectional transmission electron microscopy revealed dislocation bending by 90 at the core-shell interface and reduction in their density in the shells. V

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Photoluminescence and Raman studies of GaN films grown by MOCVD

Cited by 24 publications

References 39 publications

Facet recovery and light emission from GaN/InGaN/GaN core-shell structures grown by metal organic vapour phase epitaxy on etched GaN nanorod arrays

Facet recovery and light emission from GaN/InGaN/GaN core-shell structures grown by metal organic vapour phase epitaxy on etched GaN nanorod arrays

GaN/AlN superlattice high electron mobility transistor heterostructures on GaN/Si(111)

Large-area GaN n-core/p-shell arrays fabricated using top-down etching and selective epitaxial overgrowth

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