MOVPE growth of semipolar <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si0007.gif" overflow="scroll"><mml:mo stretchy="false">(</mml:mo><mml:mn>11</mml:mn><mml:mover accent="true"><mml:mrow><mml:mn>2</mml:mn></mml:mrow><mml:mrow><mml:mo>¯</mml:mo></mml:mrow></mml:mover><mml:mn>2</mml:mn><mml:mo stretchy="false">)</mml:mo></mml:math> AlN on m-plane <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si0008.gif" overflow="scroll"><mml:mo stretchy="false">(</mml:mo><mml:mn>10<

Stellmach, Joachim; Frentrup, Martin; Mehnke, Frank; Pristovsek, Markus; Wernicke, Tim; Kneissl, Michael

doi:10.1016/j.jcrysgro.2012.06.047

Cited by 47 publications

(75 citation statements)

References 30 publications

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“…The SiN x IL induces islanding and subsequent 3D growth, similar to observed for the growth of (0001) GaN, e.g., [26,27]. The 3D growth on (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22) induced by the SiN x IL was seen by AFM [10] and is also clearly visible in the in-situ optical reflectance transient in Fig. 2 by the reduction of the signal at 1.3 h for AlN nucleation and 2.3 h for 3D GaN nucleation.…”

Section: Resultssupporting

confidence: 54%

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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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Section: Resultssupporting

confidence: 54%

“…Since nucleation with AlN reduces the contributions of unwanted (1013)-oriented grains [15,16], subsequent GaN growth may lead to more phase pure substrates.…”

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

“…Full‐width at half‐maximum (FWHM) of the on‐axis (11

\overset{2}{true}

2) X‐ray rocking curves (XRC) of the (11

\overset{2}{true}

2) InAlN layers was estimated from the RSM scans along [1

\overset{1}{true}

00]

_{normalInAlN / italicAlN}

and [

\overset{11}{true}

23]

_{normalInAlN / italicAlN}

. The FWHM value along [

\overset{11}{true}

23] was found to be smaller than the value along [1

\overset{1}{true}

00] (Table ); this was attributed to an anisotropic crystallinity as commonly observed on (11

\overset{2}{true}

2) nitrides, e.g., InGaN (), AlN , and InN (). Both the FWHM values are larger than those for the (11

\overset{2}{true}

2) AlN templates () even though the layers are fully strained indicating that new defects were generated during InAlN growth.…”

Section: Resultsmentioning

confidence: 99%

Polar and semipolar (112) InAlN layers grown on AlN templates using MOVPE

Dinh

Parbrook

2015

Physica Status Solidi (b)

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We report on metalorganic vapor phase epitaxial growth of InAlN layers on (0001) and (11true2‾2) AlN templates at different temperatures (725–800 °C). The indium content (8.0–15.2%) of the (11true2‾2) InAlN layers was found to be lower compared to that for the (0001) layers (9.0–23.0%). The higher indium content of the (0001) layers was attributed to a high density of small hillocks and a larger degree of relaxation. The small hillocks on the (0001) layer surface acted as quantum‐dot‐like structures that caused a stronger emission at longer wavelength compared to weaker emission at shorter wavelength from a “bulk” layer underneath. A large Stokes‐shift of about 300 and 480 meV was observed for the (0001) and (11̅22) layers, respectively. The larger shift of the (11true2‾2) layers was attributed to a higher degree of localization. The larger degree of localization and higher unintentional oxygen incorporation enhanced the luminescence intensity of the (11true2‾2) layers compared to that for the (0001) layers.

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“…Moreover, nearbandgap-edge absorption of AlN epilayer was critical to UV-c light emitter or detector. Threading dislocations [37,45] and intrinsic defects [46,47] can flatten the absorption edge, compensate doping level and screen shallow doping energy level.…”

Section: Raman Scatteringmentioning

confidence: 99%

Structure, optical spectra and biaxial stress of (0002) AlN epilayers grown on c‐sapphire by high‐temperature chemical vapor deposition

Zhang

Liu

Liang

2014

Physica Status Solidi (a)

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(0002) AlN epilayers were grown on c‐sapphire at temperatures of 1100, 1200, 1300, 1400, and 1500 °C, respectively, by a homebuilt high‐temperature chemical vapor deposition system. The structure, optical properties and biaxial stress of these epilayers were characterized by scanning electronic microscope, XRD, Raman scattering, and UV absorption. The results revealed that smooth layers were obtained below 1400 °C, while stripe‐shaped and hexagon‐aligned islands grew on the surface of the layer at 1500 °C due to inhomogeneous nucleation in decreased supersaturation. Moreover, the narrowing FWHM of (0002) reflection and phonon modes indicated that the crystal quality improved with increasing temperature. The optical bandgap enlarged with the increasing growth temperature, owing to decreasing dislocations and domain boundaries as well as increasing compressive stress, except that the optical bandgap shrank at 1500 °C because light scattering at the rough surface of the epilayer flattened its optical absorption edge. Furthermore, the results of XRD and Raman studies demonstrated that the biaxial stress in the epilayers turned from tensile stress to compressive stress linearly below 1.8 GPa, resulting in a biaxial stress coefficient of −1.9 cm−1 GPa−1. Therefore, the improving structure together with the increasing biaxial compressive stress of the epilayer enlarged its optical bandgap with a large coefficient of −426 meV GPa−1.

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MOVPE growth of semipolar (112¯2) AlN on m-plane (10<

Cited by 47 publications

References 30 publications

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

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

Polar and semipolar (112) InAlN layers grown on AlN templates using MOVPE

Structure, optical spectra and biaxial stress of (0002) AlN epilayers grown on c‐sapphire by high‐temperature chemical vapor deposition

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