Evidence for Dislocation Induced Spontaneous Formation of GaN Nanowalls and Nanocolumns on Bare C-Plane Sapphire

Kesaria, Manoj; Shetty, Satish; Shivaprasad, S. M.

doi:10.1021/cg200749w

Cited by 46 publications

(47 citation statements)

References 25 publications

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“…[18][19][20][21][22] The N to Ga ratio also determines the width of the nanowalls as reported previously.…”

Section: Structural Properties Of Lmbe Grown Homoepitaxial Gan Nanostsupporting

confidence: 56%

“…Recently, a few research groups have reported the growth of GaN nanowall networks on sapphire 18,21 and Si(111) 19,20 using plasma assisted molecular beam epitaxy (PA-MBE). Most of the GaN nanowall networks have been grown heteroepitaxially on these substrates under extremely high N to Ga ux ratio conditions.…”

Section: 18-22mentioning

confidence: 99%

“…Most of the GaN nanowall networks have been grown heteroepitaxially on these substrates under extremely high N to Ga ux ratio conditions. Kesaria et al 18,22 reported that the spontaneous growth of GaN nanowall honeycomb network on sapphire ($14% lattice mismatch) is due to the presence of mist dislocations as nucleation centers on sapphire substrates. The difference in lattice constants, thermal expansion coefficients and electrical properties of the substrate and overlayer in heteroepitaxial growth can cause external biaxial strain in the GaN lms.…”

Section: 18-22mentioning

confidence: 99%

“…It has been suggested that strain due to lattice mismatch is a very important factor for occurrence of GaN nanowall network growth. 18,22 However, it would be interesting to study if GaN nanowall can also form on lattice-matched substrate.…”

Section: 18-22mentioning

confidence: 99%

“…The LMBE growth of GaN layers was monitored by in situ RHEED and the typical RHEED pattern obtained for the GaN template and the LMBE grown GaN sample along [11][12][13][14][15][16][17][18][19][20] and directions have been presented in Fig. 1(a and b).…”

Section: Structural Properties Of Lmbe Grown Homoepitaxial Gan Nanostmentioning

confidence: 99%

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Structural, optical and electronic properties of homoepitaxial GaN nanowalls grown on GaN template by laser molecular beam epitaxy

et al. 2015

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aWe have grown homoepitaxial GaN nanowall networks on GaN template using an ultra-high vacuum laser assisted molecular beam epitaxy system by ablating solid GaN target under a constant r.f. nitrogen plasma ambient. The effect of laser repetition rate in the range of 10 to 30 Hz on the structural properties of the GaN nanostructures has been studied using high resolution X-ray diffraction, field emission scanning electron microscopy and Raman spectroscopy. The variation of the laser repetition rate affected the tip width and pore size of the nanowall networks. The z-profile Raman spectroscopy measurements revealed the GaN nanowall network retained the same strain present in the GaN template. The optical properties of these GaN nanowall networks have been studied using photoluminescence and ultrafast spectroscopy and an enhancement of optical band gap has been observed for the nanowalls having a tip width of 10-15 nm due to the quantum carrier confinement effect at the wall edges. The electronic structure of the GaN nanowall networks has been studied using X-ray photoemission spectroscopy and it has been compared to the GaN template. The calculated Ga/N ratio is largest ($2) for the GaN nanowall network grown at 30 Hz. Surface band bending decreases for the nanowall network with the lowest tip width. The homoepitaxial growth of porous GaN nanowall networks holds promise for the design of nitride based sensor devices.

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“…[18][19][20][21][22] The N to Ga ratio also determines the width of the nanowalls as reported previously.…”

Section: Structural Properties Of Lmbe Grown Homoepitaxial Gan Nanostsupporting

confidence: 56%

Section: 18-22mentioning

confidence: 99%

Section: 18-22mentioning

confidence: 99%

Section: 18-22mentioning

confidence: 99%

Section: Structural Properties Of Lmbe Grown Homoepitaxial Gan Nanostmentioning

confidence: 99%

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Structural, optical and electronic properties of homoepitaxial GaN nanowalls grown on GaN template by laser molecular beam epitaxy

et al. 2015

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Nanostructuring GaN thin film for enhanced light emission and extraction

Nayak

Shamoon

Ghatak

et al. 2016

Physica Status Solidi (a)

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We demonstrate here that nanostructuring of GaN thin film significantly enhances the band‐edge emission, due to structural and geometrical effects. Films of increasing roughness are formed by kinetic control in a PA‐MBE system and their morphological, structural and optical properties are compared by complementary characterization probes. The nanowall configuration with largest pore size (≈215 nm) shows a two orders of magnitude enhancement of integrated PL intensity in comparison to a GaN epilayer. Finite difference time domain (FDTD) simulation is performed to explain the role of total internal reflection and scattering on light extraction. The extended defects terminate proximal to interface, leading to most regions of the nanowalls are defect free, enhancing light generation. The observation of broad HRXRD rocking curves is attributed to a mosaicity that originates due to mutual misorientation of the nanowalls. Thus, the low dislocation density in the nanowalls and their suitable geometry promotes high light emission and extraction, respectively, offering this nanostructure as a potential material for high brightness LED fabrication.

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Epitaxial GaN Layers: Low Temperature Growth Using Laser Molecular Beam Epitaxy Technique and Characterizations

Kushvaha

Kumar

2016

Advances in Nanomaterials

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Evidence for Dislocation Induced Spontaneous Formation of GaN Nanowalls and Nanocolumns on Bare C-Plane Sapphire

Cited by 46 publications

References 25 publications

Structural, optical and electronic properties of homoepitaxial GaN nanowalls grown on GaN template by laser molecular beam epitaxy

Structural, optical and electronic properties of homoepitaxial GaN nanowalls grown on GaN template by laser molecular beam epitaxy

Nanostructuring GaN thin film for enhanced light emission and extraction

Epitaxial GaN Layers: Low Temperature Growth Using Laser Molecular Beam Epitaxy Technique and Characterizations

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