GaN Synthesis by Ammonothermal Method

Dwiliński, R.; Wysmołek, A.; Baranowski, J. M.; Kamińska, M.; Doradziński, R.; Garczyński, J.; Sierzputowski, L.; Jacobs, H.

doi:10.12693/aphyspola.88.833

Cited by 97 publications

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“…(8)(9)(10) Despite the advantage of scalability over its counterparts, not many research institutes have attempted ammonothermal growth because the growth rate is relatively low, and high-pressure ammonothermal reactors are not commercially available. Since Dwiliński et al demonstrated bulk GaN with excellent crystal quality, (11) ammonothermal growth has drawn increasing attention from the nitride research community.…”

Section: Introductionmentioning

confidence: 99%

Ammonothermal Bulk GaN Growth and Its Processing

2014

Sensors and Materials

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In this paper, we overview the current progress of ammonothermal GaN growth at SixPoint Materials, Inc. and discuss issues in wafer processing. Bulk GaN crystals grown in small prototype reactors present a high-quality microstructure as well as an improved transparency. The dislocation density of the crystal is on the order of 4.0 × 10 4 cm −2 . The optical absorption coefficient as low as 4 cm −1 at 450 nm is obtained. Wafer processing techniques, such as wire sawing and chemical mechanical polishing, are one of the challenges in realizing GaN wafers. Crystal cracks are the major and fundamental obstacle in achieving a high-quality surface during wire sawing. The surface quality after chemical mechanical polishing (CMP) is successfully evaluated using X-ray diffraction.

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Section: Introductionmentioning

confidence: 99%

Ammonothermal Bulk GaN Growth and Its Processing

2014

Sensors and Materials

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“…In ammonothermal method used by us the chemical reaction takes place in highly active supercritical medium [2]. This fact allows to expect that temperature and pressure demands for GaN crystallization by this method would be much lower than in HNP technique.…”

Section: Introductionmentioning

confidence: 99%

On GaN Crystallization by Ammonothermal Method

et al. 1996

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GaN crystals are grown using ammonothermal method at pressures below 5 kbar and temperatures below 550°C. In this method, GaN is synthesised from high purity metallic gallium. The main role in the low temperature GaN crystallization is played by the chemically active and dense ammonia and dissolved mineralizer. Morphology of the obtained crystals as well as solubility experiments prove that gallium nitride is dissolved and crystallised from solution. Physical properties of GaN crystals obtained using ammonothermal method depend on the growth conditions and the type of mineralizer. All GaN samples reveal very intensive photoluminescence, also at room temperature. The spectra of crystals grown with lithium compound mineralizer are shifted towards higher energies in comparison to crystals grown with potassium based mineralizer. At helium temperatures, phosphorescence is also observed.

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“…If the substrate shows tilt boundaries, even if it is a native substrate but grown itself on a foreign substrate, the tilt boundaries will appear in the grown material, too [10,[37][38][39][40][41][42]. High quality of the substrate is very important, since it allows the production of more devices per substrate and devices made of low-defect-density GaN or AlN promise longer working periods at higher power without breakdown [43].…”

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Chemistry of Ammonothermal Synthesis

2014

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Ammonothermal synthesis is a method for synthesis and crystal growth suitable for a large range of chemically different materials, such as nitrides (e.g., GaN, AlN), amides (e.g., LiNH 2 , Zn(NH 2 ) 2 ), imides (e.g., Th(NH) 2 ), ammoniates (e.g., Ga(NH 3 ) 3 F 3 , [Al(NH 3 ) 6 ]I 3 · NH 3 ) and non-nitrogen compounds like hydroxides, hydrogen sulfides and polychalcogenides (e.g., NaOH, LiHS, CaS, Cs 2 Te 5 ). In particular, large scale production of high quality crystals is possible, due to comparatively simple scalability of the experimental set-up. The ammonothermal method is defined as employing a heterogeneous reaction in ammonia as one homogenous fluid close to or in supercritical state. Three types of milieus may be applied during ammonothermal synthesis: ammonobasic, ammononeutral or ammonoacidic, evoked by the used starting materials and mineralizers, strongly influencing the obtained products. There is little known about the dissolution and materials transport processes or the deposition mechanisms during ammonothermal crystal growth. However, the initial results indicate the possible nature of different intermediate species present in the respective milieus. A Alkali or alkaline-earth metal, A(1) = alkali metal, A(2) = alkaline-earth metal B Further metal, might be main group metal, transition or rare-earth metal M Transition metal, excluding Sc, Y, La R Rare-earth metal, Sc, Y, La-Lu X Halide E Other main group element

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GaN Synthesis by Ammonothermal Method

Cited by 97 publications

References 0 publications

Ammonothermal Bulk GaN Growth and Its Processing

Ammonothermal Bulk GaN Growth and Its Processing

On GaN Crystallization by Ammonothermal Method

Chemistry of Ammonothermal Synthesis

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