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The most significant disadvantage of the method is an unstable speed of growth which happens due to heat exchange changes incurred by a growing boule size and which are difficult to predict. Due to this problem the crystals are typically grown at very slow speed in order to avoid unnecessary internal
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is dipped into the molten material. The seed crystal is slowly pulled upwards and may be rotated simultaneously. By precisely controlling the temperature gradients, rate of pulling and rate of temperature decrease, it is possible to produce a large, single-crystal, roughly cylindrical ingot from the
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The sizes of sapphire crystals grown by the
Kyropoulos method have increased dramatically since the 1980s. In the mid-2000s sapphire crystals up to 30 kg were developed which could yield 150 mm diameter substrates. By 2017, the largest reported sapphire grown by the Kyropoulos method was
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of the crucible is close to that of the final crystal, and the crystal grows downward into the crucible, rather than being pulled up and out of the crucible as in the
Czochralski method. The upward pulling of the seed is at a much slower rate than the downward growth of the crystal, and serves
468:, the orientation of the cylindrical axis of the boules grown by the Kyropoulos method is perpendicular to the orientation required for deposition of GaN on the LED substrates. This means that cores must be drilled through the sides of the boule before being sliced into
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The
Kyropoulos method is characterized by smaller temperature gradients at the crystallization front than the Czochralski method. Like the Czochralski method, the crystal grows free of any external mechanical shaping forces, and thus has few
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to determine the growth rate, although precise measurements are complicated by the changing and imperfect shape of the crystal diameter, the unknown convex shape of the solid-liquid interface, and these features' interaction with
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544:"Evolution and Application of the Kyropoulos Crystal Growth Method", David F. Bliss, in "50 Years of Progress in Crystal Growth: A Reprint Collection", Ed. Robert Feigelson, Elsevier, 2005
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As of 2017 the leading manufacturers of blue and white LEDs used 150 mm diameter sapphire substrates, with some manufacturers still using 100 mm, and 2 inch substrates.
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The major advantages include technical simplicity of the process and possibility to grow crystals with large sizes (≥30 cm). The method also shows low dislocation density.
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Single crystal sapphire boule grown by
Kyropoulos method. Approximately 200 mm diameter and approximately 30 kg. (A second boule is visible in the background.)
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Dobrovinskaya, Elena R., Leonid A. Lytvynov, and
Valerian Pishchik. Sapphire: material, manufacturing, applications. Springer Science & Business Media, 2009.
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In contrast with the
Czochralski method, the Kyropoulos technique crystallizes the entire feedstock volume into the boule. The size and
213:
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142:
776:
Bruni, Frank J. (11 September 2014). "Crystal growth of sapphire for substrates for high-brightness, light emitting diodes".
738:"Status Of the Sapphire Industry." Eric Virey. Yole-CIOE Sapphire Forum, Shenzhen, August 31st 2015. Yole Development. p. 32.
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Duffar, Thierry; Sen, Gourav; Stelian, Carmen; Baruchel, José; Tran
Caliste, Thu Nhi; Barthalay, Nicolas.
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Winkler, Jan; Neubert, Michael (2015). "Automation of
Crystal Growth from Melt". In Rudolph, Peter (ed.).
690:. Kharkiv, Ukraine: Вісник національного технічного университету "ХПІ" №15 (1058). 2014. pp. 3–11.
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crystals for precision optics. The method was a response to the limited boule sizes attainable by the
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472:. This means the as-grown boules have a significantly larger diameter than the resulting wafers.
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until the entire melt has solidified. Hanging the seed from a weight sensor can provide
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The
Kyropoulos method was applied to sapphire crystal growth in the 1970s in the
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Currently the method is used by several companies around the world to produce
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The growth rate is controlled by slowly decreasing the temperature of the
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Kyropoulos, S. (1926). "Ein
Verfahren zur Herstellung großer Kristalle".
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749:"Monocrystal introduced world's first 350 kg KY sapphire crystal"
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The largest application of the Kyropoulos method is to grow large
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350 kg, and could produce 300 mm diameter substrates.
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Method of bulk crystal growth used to obtain single crystals
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650:(2nd ed.). Elsevier B.V. pp. 1176–1178.
563:Zeitschrift für Anorganische und Allgemeine Chemie
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704:Kyropoulos Crystal Growth Presentation
404:. This process can be performed in an
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173:Shaping processes in crystal growth
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815:Crystal growth technique summaries
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347:crucible.) A precisely oriented
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143:Fractional crystallization
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596:[Kyropoulos method].
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331:The feedstock is melted in a
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500:Laser-heated pedestal growth
163:Laser-heated pedestal growth
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714:. p. 4. Archived from
485:Bridgman–Stockbarger method
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153:Hydrothermal synthesis
118:Bridgman–Stockbarger method
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648:Handbook of Crystal Growth
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845:Methods of crystal growth
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123:Van Arkel–de Boer process
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575:10.1002/zaac.19261540129
277:The method is named for
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490:Monocrystalline silicon
449:and optics industries.
360:primarily to shape the
255:single crystal sapphire
128:Czochralski method
790:10.1002/crat.201400230
461:Because of sapphire's
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306:methods at the time.
238:, is a method of bulk
105:Methods and technology
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835:Industrial processes
830:Semiconductor growth
408:atmosphere, such as
364:of the solid-liquid
261:for the manufacture
236:Kyropoulos technique
230:, also known as the
97:Single crystal
77:Crystal growth
594:"МЕТОД КИРОПУЛОСА"
505:Micro-pulling-down
495:Float-zone silicon
392:within the melt.
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296:alkali earth metal
168:Micro-pulling-down
466:crystal structure
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244:single crystals
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183:Verneuil method
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23:Crystallization
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38:Fundamentals
784:: 133–142.
756:Monocrystal
569:: 308–313.
463:anisotropic
447:electronics
437:Application
300:Czochralski
282: [
138:Flux method
824:Categories
761:16 January
725:2019-04-29
632:2019-04-29
603:2019-04-29
550:0080489931
534:0387856943
511:References
420:Advantages
390:convection
345:molybdenum
319:The method
259:substrates
56:Nucleation
433:defects.
366:interface
232:KY method
840:Crystals
798:93605097
618:"Growth"
479:See also
445:for the
443:sapphire
400:and low
381:feedback
362:meniscus
341:tungsten
333:crucible
304:Verneuil
285:Wikidata
64:Concepts
377:furnace
352:melt.
273:History
265:-based
133:Epitaxy
46:Crystal
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470:wafers
414:vacuum
251:boules
113:Boules
794:S2CID
752:(PDF)
719:(PDF)
708:(PDF)
688:(PDF)
410:argon
406:inert
288:]
763:2018
660:ISBN
546:ISBN
530:ISBN
388:and
368:via
302:and
294:and
267:LEDs
226:The
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652:doi
571:doi
567:154
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Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
