Preparation of Free-Standing GaN Substrates from Thick GaN Layers Crystallized by Hydride Vapor Phase Epitaxy on Ammonothermally Grown GaN Seeds

Sochacki, Tomasz; Bryan, Zachary; Amilusik, Mikolaj; Collazo, Ramón; Łucznik, B.; Weyher, J.L.; Nowak, G.; Sadovyi, B.; Kamler, G.; Kucharski, Robert; Zając, M.; Doradziński, R.; Dwiliński, R.; Grzegory, I.; Boćkowski, Michał; Sitar, Zlatko

doi:10.7567/apex.6.075504

Cited by 57 publications

(67 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…3 Sochacki et al have shown that low dislocation density ammonothermally grown GaN crystals can be successfully used as seeds for the HVPE growth and it is possible to combine the benefits of both growth methods, ammonothermal growth method and HVPE, and crystallize low dislocation density GaN crystals. 4,5 The lattice parameter of the ammonothermal GaNseed material and the grown HVPE-GaN crystals had the same values within the experimental error (a = 318.97 ± 0.02 pm and c = 518.51 ± 0.01 pm) showing that no stress was introduced. Moreover the HRXRD 0002 rocking-curve full widths at half maximum (FWHM) of the HVPE crystals of approximately 40 arcsec were in the same order of magnitude as the ammonothermal seed material.…”

supporting

confidence: 57%

Synchrotron White-Beam X-Ray Topography Analysis of the Defect Structure of HVPE-GaN Substrates

Kirste

Danilewsky

Sochacki

et al. 2015

ECS J. Solid State Sci. Technol.

View full text Add to dashboard Cite

The defect structure of HVPE-GaN crystals is examined using synchrotron white-beam X-ray topography (SWXRT) and topography results are interpreted and discussed in comparison to reciprocal lattice point broadening from high resolution X-ray diffraction (HRXRD) measurements. Two as-received commercial HVPE-GaN wafers from two different vendors and one HVPE-GaN which was grown on an ammonothermal GaN-seed are investigated in this study. To our knowledge SWXRT large area back-reflection analysis of HVPE-GaN grown on an ammonothermal GaN seed has been performed for the first time. From large-area topography the formation of a cellular defect network is identified for the commercial HVPE-GaN. Large differences in the crystal lattice misorientation deformation (mosaicity) are determined for the different samples by transmission section topography. For the HVPEGaN grown on an ammonothermal GaN-seed a very low defect density was ascertained. From the contrasts of the topography threading screw-type dislocations and threading mixed-type dislocations were identified. The X-ray topography analysis shows clearly and for the first time that the nature of the defect structure and the low density of ammonothermal GaN seeds can be transferred by HVPE growth of GaN. For demanding GaN-based (opto-)electronic applications such as laser diodes or transistors for high power electronics there is a need for material with low defect densities, since threading dislocations act as centers of non-radiative recombination, increasing the leakage current, reducing the room temperature mobility and so limiting the efficiency, performance and lifetime of devices. Freestanding GaN with low defect density is the substrate material of choice for the realization of such GaN-based device structures with superior properties. Different approaches for crystal growth of bulk GaN like ammonothermal growth, hydride vapor-phase epitaxy (HVPE) and high-and low-pressure solution growth were followed in recent years.1 The ammonothermal growth and HVPE seem to be the most promising methods to produce GaN substrates in sufficient number, size and material quality and substrates prepared with these growth methods have become available commercially in recent years. In the ammonothermal growth method, GaN crystalizes from a solution of Ga in supercritical ammonia with the addition of a mineralizer. For seed material, the ammonothermal growth method uses native GaN crystals. Benefits of the ammonothermal growth method are very low dislocation densities as low as 5 × 10 3 cm −2 and large curvature radii of the crystal planes (>100 m).2 Drawbacks of GaN ammonothermal growth method are the incorporation of impurities and the low growth rate (0.1 mm/day), even when the method can potentially produce hundreds of crystals in a single batch. In comparison, in HVPE the GaN crystallization takes place from the vapor phase by the reaction of ammonia with gallium chloride at temperatures of about 1050• C. HVPE uses GaN seed layers (templates) deposited e.g. by metalorganic v...

show abstract

supporting

confidence: 57%

Synchrotron White-Beam X-Ray Topography Analysis of the Defect Structure of HVPE-GaN Substrates

Kirste

Danilewsky

Sochacki

et al. 2015

ECS J. Solid State Sci. Technol.

View full text Add to dashboard Cite

show abstract

“…A basic understanding of the sub-bandgap absorption behavior of GaN for wavelengths between 360 nm and 800 nm can be gleaned from the few existing reports which performed optical absorption measurements on epitaxial GaN films grown on sapphire substrates using photothermal deflection spectroscopy (PDS) 1,2,3,4 and optical transmission method 5 , along with a few isolated measurements using optical transmission measurements on bulk GaN crystals grown by the ammonothermal method 6 or hydride vapor phase epitaxy (HVPE) 7 . No report was found which systematically investigated the dependence of sub-bandgap absorption of high quality, bulk GaN crystals on free electron concentration (FEC).…”

Section: Introductionmentioning

confidence: 99%

Free electron concentration dependent sub-bandgap optical absorption characterization of bulk GaN crystals

Pimputkar

Suihkonen

Imade

et al. 2015

Journal of Crystal Growth

View full text Add to dashboard Cite

Optical transmission measurements were performed on high quality bulk gallium nitride (GaN) crystals grown by sodium flux, hydride vapor phase epitaxy, and the ammonothermal method with varying free electron concentrations ranging from 4x10 16 cm -3 to 9x10 18 cm -3 . The quality of the crystals was analyzed by Xray diffraction, threading dislocation density determination, impurity concentrations, and Hall mobility measurements. The sub-bandgap absorption coefficient and index of refraction was determined based on illumination wavelengths ranging from 360 nm to 800 nm. Phonon-assisted free carrier absorption was determined to be the dominant absorption mechanism above approximately 0.1 cm -1 . The absorption coefficient at 450 nm varied linearly from 0.1 cm -1 to 5 cm -1 for free electron concentrations ranging from 1x10 17 cm -3 to 9x10 18 cm -3 . The ammonothermal GaN samples exhibited a strong defect related onset of absorption above 2.9 eV which can be explained by the presence of appreciable hydrogenated gallium vacancies having defect states close to the 2 valance band within the electric bandgap of GaN. The presence of hydrogenated gallium vacancies was experimentally confirmed by Fourier transform infrared absorbance measurements and double hydrogenated gallium vacancy defect are speculated to be prominent in ammonothermal GaN.

show abstract

“…Due to self-separation from the sapphire, a 2-inch free standing HVPE-GaN crystal can be obtained 15 . On the other hand, FS HVPE-GaN can be also obtained by using ammonothermally grown GaN as seed (Am-GaN) 16 . 1-inch Am-GaN crystals, with misorientation ~0.3 degree to the m direction and the (0001) surfaces prepared by mechano-chemical polishing and then cleaning to the epi-ready state, are used.…”

Section: Methodsmentioning

confidence: 99%

Bulk GaN and its application as substrates in building quantum nanostructures for some electronic and optoelectronic devices

Boćkowski

2014

SPIE Proceedings

View full text Add to dashboard Cite

The use of GaN crystals grown by three methods (and their combinations): Hydride Vapor Phase Epitaxy (HVPE), high nitrogen pressure solution (HNPS) and ammonothermal method for optoelectronic (laser diodes) and electronic (transistors) devices is presented. After a brief review on the development of the three crystallization methods, the GaN crystals' uniform and unique properties, which allow to use them as substrates for building devices, are shown. The Metal Organic Vapor Phase Epitaxy (MOCVD) and Molecular Beam Epitaxy (MBE) technologies for growing the nitride quantum nanostructures as well as the structures' properties and processing of devices are demonstrated. Future challenges and perspectives for application of bulk GaN as substrates in building quantum nanostructures for some electronic and optoelectronic devices are discussed.

show abstract

Preparation of Free-Standing GaN Substrates from Thick GaN Layers Crystallized by Hydride Vapor Phase Epitaxy on Ammonothermally Grown GaN Seeds

Cited by 57 publications

References 9 publications

Synchrotron White-Beam X-Ray Topography Analysis of the Defect Structure of HVPE-GaN Substrates

Synchrotron White-Beam X-Ray Topography Analysis of the Defect Structure of HVPE-GaN Substrates

Free electron concentration dependent sub-bandgap optical absorption characterization of bulk GaN crystals

Bulk GaN and its application as substrates in building quantum nanostructures for some electronic and optoelectronic devices

Contact Info

Product

Resources

About