N-polar GaN evolution on nominally on-axis c-plane sapphire by MOCVD Part-II: Microstructural investigation

Saha, Sabyasachi; Yaddanapudi, Krishna; Channagiri, Samartha; Muraleedharan, K.; Banerjee, D.

doi:10.1016/j.mseb.2022.116004

Cited by 2 publications

(1 citation statement)

References 49 publications

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“…Unlike Ga-polar GaN growth [32][33][34][35], the origin of the rougher surface of Npolar GaN is not clear. Using MOCVD growth, the N-polar GaN growth evolution on on-axis sapphire [25,36,37], the effect of the AlN on the morphology [24,38], and the GaN growth conditions [39][40][41] have been widely studied. The typical PA-MBE-grown Ga-polar GaN on on-axis Si-face SiC has also been widely reported to proceed through the screwtype dislocation-mediated step-flow growth mechanism [42].…”

Section: Introductionmentioning

confidence: 99%

Surface morphology evolution of N-polar GaN on SiC for HEMT heterostructures grown by plasma-assisted molecular beam epitaxy

Huo¹,

Lingaparthi²,

Dharmarasu³

et al. 2023

J. Phys. D: Appl. Phys.

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The surface morphology evolution of N-polar GaN with growth time was investigated and compared with Ga-polar GaN. N-polar GaN directly grown on SiC substrates was found to have slower three-dimensional (3D) to two-dimensional (2D) growth transformation and lesser coalescence than the Ga-polar counterpart, resulting in rougher surface morphology, whereas the AlN nucleation layer (NL) accelerated 3D to 2D transformation, resulting in smoother surface morphology. N-polar GaN was found to have mound-type surface morphology with clustered atomic steps, unlike the regular screw-type dislocation-mediated step-flow growth observed for Ga-polar GaN. This was explained by the lower diffusion of adatoms on the N-polar surface due to its higher surface energy and higher Ehrlich-Schwoebel barrier (ESB). In addition, the increased III/V ratio in N-polar GaN growth was found to reduce the surface roughness from 2.4 nm to 1 nm. Without Si doping, the N-polar GaN HEMT heterostructures grown under optimized conditions with smoother surface morphologies exhibited sheet carrier density of 0.91 × 1013 cm-2 and mobility of 1220 cm2/V∙s. With Si δ-doping, the sheet carrier density was increased to 1.28 × 1013 cm-2 while the mobility was reduced to 1030 cm2/V∙s. These results are comparable to the state-of-the-art data of PA-MBE-grown N-polar GaN HEMT heterostructures on SiC substrates.

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Section: Introductionmentioning

confidence: 99%

Surface morphology evolution of N-polar GaN on SiC for HEMT heterostructures grown by plasma-assisted molecular beam epitaxy

Huo¹,

Lingaparthi²,

Dharmarasu³

et al. 2023

J. Phys. D: Appl. Phys.

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Metalorganic Vapor‐Phase Epitaxy of +c/−c GaN Polarity Inverted Bilayer for Transverse Quasi‐Phase‐Matched Wavelength Conversion Device

Ikeda,

Malik,

Uemukai

et al. 2024

Physica Status Solidi (b)

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Photon‐pair generation based on optical parametric down‐conversion has attracted for the application as a light source for quantum information. Highly efficient wavelength‐conversion devices require a polarity‐inversion structure when using nitride semiconductors. A transverse quasi‐phase‐matching (QPM) polarity‐inverted GaN bilayer channel waveguide device is suitable for efficient wavelength conversion. This study designed a cross‐section device to satisfy the modal dispersion phase‐matching condition between the TM02 mode pump light and the TM00 mode signal/idler light. Moreover, an AlN oxidation interlayer fabricates the Ga‐polar/N‐polar (+c/−c) GaN layers via metalorganic vapor‐phase epitaxy (MOVPE). A 145 nm thick film layer with a macro‐step‐free surface is grown by optimizing the −c‐GaN growth conditions and reducing the substrate off‐angle to 0.2°. Next, the AlN layer is oxidized in an electric furnace and MOVPE is used to regrow a 1500 nm thick +c‐GaN layer. A macrosteps‐free surface can be achieved by reducing the off‐angle to 0.2° and optimizing the −c‐GaN growth conditions to avoid hillock formation. These results pave the way for improving the efficiency of GaN transverse QPM wavelength‐conversion devices.

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N-polar GaN evolution on nominally on-axis c-plane sapphire by MOCVD Part-II: Microstructural investigation

Cited by 2 publications

References 49 publications

Surface morphology evolution of N-polar GaN on SiC for HEMT heterostructures grown by plasma-assisted molecular beam epitaxy

Surface morphology evolution of N-polar GaN on SiC for HEMT heterostructures grown by plasma-assisted molecular beam epitaxy

Metalorganic Vapor‐Phase Epitaxy of +c/−c GaN Polarity Inverted Bilayer for Transverse Quasi‐Phase‐Matched Wavelength Conversion Device

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