Ion-assisted nucleation and growth of GaN on sapphire(0001)

Headrick, Randall L.; Kycia, S.; Woll, Arthur R.; Brock, J. D.; Murty, M. V. R. K.

doi:10.1103/physrevb.58.4818

Cited by 25 publications

(24 citation statements)

References 43 publications

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“…Because this sticking probability depends strongly on the substrate, a quartz crystal monitor is an inappropriate measure of growth rate. This phenomena has been observed in other systems: in metalorganic based GaN growth on sapphire, both growth rate acceleration 14 and deceleration 24 have been observed using in situmeasurements of Ga Kα x-ray fluorescence.…”

Section: Introductionmentioning

confidence: 80%

Quantitative modeling ofin situx-ray reflectivity during organic molecule thin film growth

2011

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Synchrotron-based x-ray reflectivity is increasingly employed as an in situ probe of surface morphology during thin film growth, but complete interpretation of the results requires modeling the growth process. Many models have been developed and employed for this purpose, yet no detailed, comparative studies of their scope and accuracy exists in the literature. Using experimental data obtained from hyperthermal deposition of pentane and diindenoperylene (DIP) on SiO2, we compare and contrast three such models, both with each other and with detailed characterization of the surface morphology using ex-situ atomic force microscopy (AFM). These two systems each exhibit particular phenomena of broader interest: pentacene/SiO2 exhibits a rapid transition from rough to smooth growth. DIP/SiO2, under the conditions employed here, exhibits growth rate acceleration due to a different sticking probability between the substrate and film. In general, independent of which model is used, we find good agreement between the surface morphology obtained from fits to the in situx-ray data with the actual morphology at early times. This agreement deteriorates at later time, once the root-mean squared (rms) film roughness exceeds about 1 ML. A second observation is that, because layer coverages are under-determined by the evolution of a single point on the reflectivity curve, we find that the best fits to reflectivity data -corresponding to the lowest values of χ 2 ν -do not necessarily yield the best agreement between simulated and measured surface morphologies. Instead, it appears critical that the model reproduce all local extrema in the data. In addition to showing that layer morphologies can be extracted from a minimal set of data, the methodology established here provides a basis for improving models of multilayer growth by comparison to real systems.

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Section: Introductionmentioning

confidence: 80%

Quantitative modeling ofin situx-ray reflectivity during organic molecule thin film growth

2011

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“…Fused quartz tubes assembled with o-ring seals are used for the following items: the x-ray transparent chamber wall (6); the low-thermal-expansion support for the heated sample mount (7); and the input flow tubes for group III (8) and group V (9) channels. The quartz tube forming the x-ray transparent chamber wall has a 70 mm inner diameter and 2 mm wall thickness.…”

Section: System Design a Growth Chambermentioning

confidence: 99%

“…By revealing the development of atomicscale surface morphology, strain, and defects in real time during growth, it provides understanding of the impact of growth conditions on film and interface structures, and thus optical or electronic properties. Examples of film growth processes for III-nitride semiconductors studied to date using in situ x-ray techniques include metal-organic vapor phase epitaxy (MOVPE), 1-7 molecular beam epitaxy (MBE), [8][9][10] and sputtering. 11 Research programs using standard laboratory x-ray sources [4][5][6][7]11 for in situ studies typically monitor specular reflectivity or diffraction in the Bragg geometry, which gives sufficient intensity for real-time measurements.…”

Section: Introductionmentioning

confidence: 99%

“…In situ studies at a synchrotron [1][2][3][8][9][10] can employ the higher x-ray brilliance for surface-sensitive techniques such as grazing incidence x-ray scattering, 12 as well as fast-scan reciprocal space mapping and observation of weak features such as crystal truncation rods (CTRs), fractional-order peaks, diffuse scattering and diffraction a) Author to whom correspondence should be addressed. Electronic mail:gju@anl.gov b) Electronic mail: gbs@anl.gov from ultrathin films.…”

Section: Introductionmentioning

confidence: 99%

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An instrument for in situ coherent x-ray studies of metal-organic vapor phase epitaxy of III-nitrides

Highland

Yanguas‐Gil

et al. 2017

Review of Scientific Instruments

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We describe an instrument that exploits the ongoing revolution in synchrotron sources, optics, and detectors to enable in situ studies of metal-organic vapor phase epitaxy (MOVPE) growth of III-nitride materials using coherent x-ray methods. The system includes high-resolution positioning of the sample and detector including full rotations, an x-ray transparent chamber wall for incident and diffracted beam access over a wide angular range, and minimal thermal sample motion, giving the sub-micron positional stability and reproducibility needed for coherent x-ray studies. The instrument enables surface x-ray photon correlation spectroscopy, microbeam diffraction, and coherent diffraction imaging of atomic-scale surface and film structure and dynamics during growth, to provide fundamental understanding of MOVPE processes.

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“…In conventional condensation theory, where nucleation rates are limited by energetic barriers, the nucleation process is also often characterized by a significant time lag [7]. So far, the only in situ nucleation studies of GaN have been restricted to techniques such as reflection high-energy electron diffraction (RHEED) [8,9] and real-time X-ray scattering [10][11][12]. With line-of-sight quadrupole mass spectrometry we developed a unique in situ method that also facilitates a quantitative determination of the growth rate by monitoring the amount of desorbing Ga atoms from the growing surface.…”

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confidence: 99%

Nucleation Phenomena during Molecular Beam Epitaxy of GaN Observed by Line-of-Sight Quadrupole Mass Spectrometry

Koblmüller

Pongratz

Averbeck

et al. 2002

phys. stat. sol. (a)

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We investigate nucleation and growth phenomena during molecular beam epitaxy of GaN on sapphire, 6H‐SiC and GaN templates using in situ line‐of‐sight quadrupole mass spectrometry. Moreover, this method allows the quantitative study of nucleation phenomena by monitoring desorption processes. Heteroepitaxial growth of GaN on sapphire and 6H‐SiC faces a high energy barrier to nucleation giving rise to a substantial Ga desorption during the initial phase of nucleation. The amount of initial Ga desorption in heteroepitaxy is independent of the chosen substrate material and is as high as 8 ± 1.5 nm equivalent GaN thickness. Once critical‐sized islands have nucleated they grow three‐dimensional (3D) leading to a quadratic increase of the GaN coverage and finally to a steady growth rate after coalescence, as also determined by Rutherford backscattering and atomic force microscopy. In contrast, homoepitaxy on Ga‐ and N‐face GaN templates is distinguished by immediate nucleation.

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Ion-assisted nucleation and growth of GaN on sapphire(0001)

Cited by 25 publications

References 43 publications

Quantitative modeling ofin situx-ray reflectivity during organic molecule thin film growth

Quantitative modeling ofin situx-ray reflectivity during organic molecule thin film growth

An instrument for in situ coherent x-ray studies of metal-organic vapor phase epitaxy of III-nitrides

Nucleation Phenomena during Molecular Beam Epitaxy of GaN Observed by Line-of-Sight Quadrupole Mass Spectrometry

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