Improvement of (11-22) GaN on m-Plane Sapphire With CrN Interlayer by Using Molecular Beam Epitaxy

Liu, Kuang-Wei; Chang, Shoou–Jinn; Young, Sheng-Joue; Hsueh, Ting-Jen; Hung, Hung; Mai, Yu-Chun; Wang, Shih-Ming; Chen, Yue-Zhang

doi:10.1149/1.3615957

Cited by 13 publications

(42 citation statements)

References 19 publications

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“…Different interlayer methods have been tried to reduce threading dislocations by promoting 3D growth. Exotic elements have been tried like ScN (), CrN (), as well as more common elements like InN quantum dots (), or SiN x interlayers . While these reduce XRD

ω

FWHM, they often lead to very rough surfaces.…”

Section: Introductionmentioning

confidence: 99%

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Optimizing GaN () hetero‐epitaxial templates grown on () sapphire

Pristovsek

Frentrup

Han

et al. 2015

Physica Status Solidi (b)

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The hetero‐epitaxy of (11true2‾2) GaN on (10true1‾0) sapphire was optimized in metal–organic vapor phase epitaxy. Best results were obtained from an AlN nucleation followed by AlN and AlGaN layers, and inserting low‐temperature AlN interlayers (ILs) as well as a SiNx IL. X‐ray diffraction (XRD) of ω scans of the symmetric (11true2‾2) reflection yielded an ω FWHM <450″ along [11true2‾true3‾] and <900″ along [10true1‾0] together with a 100×100thinmathspaceμm2 rms roughness below 10 nm as determined by atomic force microscopy. The lowest threading dislocation density achieved was ≈109cm−2 while the basal plane stacking fault density was in the lower 105cm−1 range as determined by transmission electron microscopy. The suppression of the unwanted (10true1‾true3‾) phase was lower than 1 in 10,000 as judged from XRD.

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ω

FWHM, they often lead to very rough surfaces.…”

Section: Introductionmentioning

confidence: 99%

“…Exotic elements have been tried like ScN [7], CrN [8], as well as more common elements like InN quantum dots [9], or SiN x interlayers [10,11]. While these reduce XRD ω FWHM, they often lead to very rough surfaces.…”

mentioning

confidence: 99%

Optimizing GaN () hetero‐epitaxial templates grown on () sapphire

Pristovsek

Frentrup

Han

et al. 2015

Physica Status Solidi (b)

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show abstract

“…But such layers have a huge density of dislocations in the

10^{10} {cm}^{- 2}

range and basal‐plane stacking faults (BSFs) in the

10^{5} {cm}^{- 1}

range . To reduce defects by promoting three dimensional growth several interlayers have been used like ScN (), CrN (), InN quantum dot (), or SiN

_{x}

interlayers. Still these do not reduce BSFs below

10^{5}

^{- 1}

.…”

Section: Introductionmentioning

confidence: 99%

Low defect large area semi‐polar (112) GaN grown on patterned (113) silicon

Pristovsek

Han

Zhu

et al. 2014

Physica Status Solidi (b)

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We report on the growth of semi-polar GaN (112) templates on patterned Si (113) substrates. Trenches were etched in Si (113) using KOH to expose Si {111} sidewalls. Subsequently an AlN layer to prevent meltback etching, an AlGaN layer for stress management, and finally two GaN layers were deposited. Total thicknesses up to 5 m were realised without cracks in the layer. Transmission electron microscopy showed that most dislocations propagate along [0001] direction and hence can be covered by overgrowth from the next trench. The defect densities were below and stacking fault densities less than 100 cm . These numbers are similar to reports on patterned r-plane sapphire. Typical X-ray full width at half maximum (FHWM) were 500” for the asymmetric (00.6) and 450” for the (11.2) reflection. These FHWMs were 50 % broader than reported for patterned r-plane sapphire which is attributed to different defect structures and total thicknesses. The surface roughness shows strong variation on templates. For the final surface roughness the roughness of the sidewalls of the GaN ridges at the time of coalescence are critical.

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“…This typically results in a threading dislocation density (TDD) of low 10 8 cm −2 on sapphire and closer to 10 9 cm −2 on silicon. The variation in TDD has an impact on the EQE, which was shown for LEDs emitting at wavelengths shorter than 460 nm [1][2][3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Effects of Wavelength and Defect Density on the Efficiency of (In,Ga)N-Based Light-Emitting Diodes

et al. 2017

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We measured the electro-luminescence of light emitting diodes (LEDs) on substrates with low dislocation densities (LDD) at 10 6 cm −2 and low 10 8 cm −2 , and compared them to LEDs on substrates with high dislocation densities (HDD) closer to 10 10 cm −2. The external quantum efficiencies (EQEs) were fitted using the ABC-model with and without localisation. The non-radiative recombination (NR) coefficient A was constant for HDD LEDs, indicating that the NR was dominated by dislocations at all wavelengths. However, A strongly increased for LDD LEDs by a factor of twenty when increasing the emission wavelength from 440 nm to 540 nm. We attribute this to an increased density of point defects due to the lower growth temperatures used for longer wavelengths. The radiative recombination coefficient B followed the squared wave function overlap for all samples. Using the observed coefficients, we calculated the peak efficiency as a function of the wavelength. For HDD LEDs the change of wave function overlap (i.e. B) is sufficient to reduce the EQE as observed, while for LDD LEDs also the NR coefficient A must increase to explain the observed EQEs. Thus reducing NR is important to improve the EQEs of green LEDs, but this cannot be achieved solely by reducing the dislocation density: point defects must also be addressed.

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Improvement of (11-22) GaN on m-Plane Sapphire With CrN Interlayer by Using Molecular Beam Epitaxy

Cited by 13 publications

References 19 publications

Optimizing GaN () hetero‐epitaxial templates grown on () sapphire

Optimizing GaN () hetero‐epitaxial templates grown on () sapphire

Low defect large area semi‐polar (112) GaN grown on patterned (113) silicon

Effects of Wavelength and Defect Density on the Efficiency of (In,Ga)N-Based Light-Emitting Diodes

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