Grain Expansion and Subsequent Seeded Growth of AlN Single Crystals

2004 ◽  
Vol 831 ◽  
Author(s):  
Dejin Zhuang ◽  
Raoul Schlesser ◽  
Zlatko Sitar
Keyword(s):  
Single Crystals ◽  
Growth Process ◽  
Surface Preparation ◽  
Nitrogen Atmosphere ◽  
Vapor Transport ◽  
Growth Surface ◽  
Seeded Growth ◽  
Single Crystalline ◽  
High Temperature Reactor

ABSTRACTOngoing efforts of growing large AlN single crystals at NCSU using an induction-heated, high-temperature reactor are based on (1) engineered expansion of single crystalline grains with increasing boule length, as well as (2) the development of a growth process that enables seeded growth on AlN surfaces previously exposed to air. The growth process is based on physical vapor transport (PVT), where AlN powder is sublimed in a high purity nitrogen atmosphere. The growth temperature was typically in the range of 2250 to 2300 °C. In this study, tungsten crucibles were used in combination with graphite insulation and were found to be durable for AlN growth. Boule growth was interrupted several times in order to refill the AlN powder source and the growth surface was subjected to surface preparation to facilitate epitaxial re-growth. Grain expansion was studied as a function of process parameters. Crystalline quality of large single crystalline grains was correlated with their surface morphology.

scholarly journals The Physical Vapor Transport Method for Bulk AlN Crystal Growth

Molecules ◽  
2019 ◽  
Vol 24 (8) ◽  
pp. 1562 ◽  
Author(s):  
Wen-Hao Chen ◽  
Zuo-Yan Qin ◽  
Xu-Yong Tian ◽  
Xu-Hui Zhong ◽  
Zhen-Hua Sun ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Temperature Gradient ◽  
Single Crystals ◽  
Low Cost ◽  
Vapor Transport ◽  
Physical Vapor Transport ◽  
Inverse Temperature ◽  
Seeded Growth ◽  
Perforated Sheet

In this report, the development of physical vapor transport (PVT) methods for bulk aluminum nitride (AlN) crystal growth is reviewed. Three modified PVT methods with different features including selected growth at a conical zone, freestanding growth on a perforated sheet, and nucleation control with an inverse temperature gradient are discussed and compared in terms of the size and quality of the bulk AlN crystals they can produce as well as the process complexity. The PVT method with an inverse temperature gradient is able to significantly reduce the nucleation rate and realize the dominant growth of only one bulk AlN single crystal, and thus grow centimeter-sized bulk AlN single crystals. X-ray rocking curve (XRC) and Raman spectroscopy measurements showed a high crystalline quality of the prepared AlN crystals. The inverse temperature gradient provides an efficient and relatively low-cost method for the preparation of large-sized and high-quality AlN seed crystals used for seeded growth, devoted to the diameter enlargement and quality improvement of bulk AlN single crystals.

Growth of Large Diameter 6H SI and 4H n+ SiC Single Crystals

2010 ◽  
Vol 1246 ◽  
Author(s):  
Avinash Gupta ◽  
Ping Wu ◽  
Varatharajan Rengarajan ◽  
Xueping Xu ◽  
Murugesu Yoganathan ◽  
...  
Keyword(s):  
Single Crystals ◽  
Growth Process ◽  
Large Diameter ◽  
Commercial Production ◽  
High Resistivity ◽  
Steady Growth ◽  
Vanadium Doping ◽  
Low Capacitance ◽  
Very High

AbstractSiC single crystals are grown at II-VI by the seeded sublimation technique. The process has been scaled up and optimized to support commercial production of high-quality 100 mm diameter, Semi-Insulating (SI) 6H substrates and 100 mm 4H n+ substrates. The growth process incorporates special elements aimed at achieving uniform sublimation of the source, steady growth rate, uniform doping and reduced presence of background impurities.Semi-insulating 6H substrates are produced using precise vanadium compensation. Vanadium doping is optimized to yield SI material with very high resistivity and low capacitance.Crystal quality of the substrates is evaluated using a wide variety of techniques. Specific defects, their interaction and evolution during growth are described with emphasis on micropipes and dislocations. The current quality of the 6H SI and 4H n+ crystals grown at II-VI is summarized.

Seeded growth of AlN single crystals by physical vapor transport

2006 ◽  
Vol 287 (2) ◽  
pp. 372-375 ◽  
Author(s):  
D. Zhuang ◽  
Z.G. Herro ◽  
R. Schlesser ◽  
Z. Sitar
Keyword(s):  
Single Crystals ◽  
Vapor Transport ◽  
Physical Vapor Transport ◽  
Seeded Growth

scholarly journals Подготовка поверхности материалов для создания композитных оптических элементов

2020 ◽  
Vol 90 (11) ◽  
pp. 1913
Author(s):  
М.В. Зорина ◽  
И.И. Кузнецов ◽  
М.С. Михайленко ◽  
О.В. Палашов ◽  
А.Е. Пестов ◽  
...  
Keyword(s):  
Single Crystals ◽  
Grazing Angle ◽  
Surface Preparation ◽  
Yttrium Aluminium Garnet ◽  
Laser Materials ◽  
Ion Etching ◽  
Yttrium Aluminium

The quality of surface preparation of various laser materials for the purpose of creating composite elements is studied. It is shown that the flatness of the samples should be no worse than λ/10, and the roughness - no more than 1.0 nm. Parameters of ion etching that do not lead to roughness degradation are found: Ar ions, Eion=800 eV and grazing angle θ=5º. Composite elements were created from yttrium aluminium garnet doped with ytterbium ions (Yb:YAG), as well as a magnetoactive TGG crystal with single crystals of sapphire.

scholarly journals Seeded growth of high-quality transition metal dichalcogenide single crystals via chemical vapor transport

CrystEngComm ◽  
2020 ◽  
Vol 22 (46) ◽  
pp. 8017-8022
Author(s):  
Hao Li ◽  
Junku Liu ◽  
Nan Guo ◽  
Lin Xiao ◽  
Haoxiong Zhang ◽  
...  
Keyword(s):  
Transition Metal ◽  
Single Crystals ◽  
Chemical Vapor ◽  
Vapor Transport ◽  
Chemical Vapor Transport ◽  
Transition Metal Dichalcogenide ◽  
Seeded Growth ◽  
High Quality ◽  
Short Period

Seeded chemical vapor transport growth gives high-quality and millimeter-sized transition metal dichalcogenide single crystals in a short period.

Growth of AlN bulk crystals from the vapor phase

2001 ◽  
Vol 693 ◽  
Author(s):  
Raoul Schlesser ◽  
Rafael Dalmau ◽  
Rositza Yakimova ◽  
Zlatko Sitar
Keyword(s):  
Single Crystals ◽  
Vapor Phase ◽  
Growth Direction ◽  
Nitrogen Atmosphere ◽  
Bulk Crystals ◽  
Seeded Growth ◽  
Long Term Stability ◽  
Dislocation Densities ◽  
Very High

AbstractAlN single crystals were grown by two different vapor phase processes: by vaporization of metallic Al in a nitrogen atmosphere, or by sublimation of an AlN source. Growth experiments were carried out under quasi-stagnant flow conditions, with typical flow rates of 100 sccm at reactor pressures ranging from 300 to 700 Torr. Growth temperatures ranged from 1800 to 2300°C. In Al vaporization experiments, the crystal shape and fastest growth direction was found to strongly depend on the growth temperature: at relatively low temperatures (1800-1900°C) long needles were grown, temperatures around 1900-2000°C yielded twinned platelets, while c-platelets were formed at temperatures above 2100°C. These c-plates grew at a rate of 5 mm/hr in the c-plane. When using AlN as a source material, growth rates were considerably slower, however, long-term stability of the Al flux was greatly improved. Seeded growth was demonstrated under these conditions. All grown single crystals were transparent and virtually colorless. Analytical results indicated very high crystalline quality and dislocation densities lower than 104cm-3.

Knoop Hardness on the (0001) Plane of 4H and 6H SiC Single Crystals Fabricated by Physical Vapor Transport

2014 ◽  
Author(s):  
Jeffrey J. Swab ◽  
James W. McCauley ◽  
Brady Butler ◽  
Daniel Snoha ◽  
Donovan Harris ◽  
...  
Keyword(s):  
Single Crystals ◽  
Knoop Hardness ◽  
Vapor Transport ◽  
Physical Vapor Transport
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