南邮材料化学MC2016-Chapter5-b

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焰熔法
Growth of Rutile with flame melt method
Rutile crystal
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5) liquid phase epitaxy method
• Melt was contain in boat, when it move through the single crystal substrate, it was cooled and form a nuclear and grow epitaxy.
– move the solvent by evaporation. Water and melting salt (for inorganic crystal growth) Alcohol and acetone (for organic crystal growth)
solution
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1) Aqueous solution method
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Growth of quartz and Irish diamond
convection
quartz
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Application of Hydrothermal Method
※ Monocrystal Growth
Application (1) Monocrystal Growth
Grow the monocrystal in a low temperature, thus avoid the physical defects induced by the phase change.
• When the melt is different, you can prepare single film of different composition.
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液相外延法
Liquid phase epitaxy system
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Advantages：
• Simple device, quick, purity is high, many doping agent can be selected, few dislocation, can control the composition and thick easily, repeatable, safe.
5.4 Crystal growth technique
Key terms: melt growth method, solution
growth method, super cool, pulling method,
crucible pot descent method, zone melting
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• Temperature often used is 1000C
• Inorganic solvent may decrease the melting
point f solute, so it can be used to prepare
compound with high melting point (such as
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5.4.2
Solution growth method
• Principle: prepare the supersaturated solution
• Approach for supersaturated： ??
– Increase or decrease the temperature;
• Fix the heater and move the raw material stick is also OK. 12
Moving direction?
区熔法
Level zone melt method
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Zone melt method contain compound
InP single crystal InP单晶的合成
※ Flame fusion method
※ Liquid phase epitaxy method
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1) Pulling method
Ar + 1~2% O2
• Super-cooling
• Few dislocation
• Rapid and big
• Good quality
For growth of single crystal, such as Ge, Si,
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5.4.1
Melt growth method
——the raw material was melt, then it was super cooled to form single crystal.
※ Pulling method ※ Crucible pot descent method ※ Zone melting method
?
CdTe single crystal
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200 mm long, d=75 mm GaAs
d=100 mm InP single crystal and crystal chip
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4) Flame melt method
Hammer 1 strike the raw powder material 2, when it arrive at position 6, H2 and O2 flame were input to melt the raw material, when it fall to the seed, it grows slowly. Can grow big crystal (1 meter); be adapt to grow compound crystal with high melting points; not polluted; inner force is big. Such as growth of precious stone
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※ Film Preparation

Can get fine CaTiO3 type compound
film or thick film under very low
(3) Film Preparation
temperature, such as BaTiO3, SrTiO3,
BaFeO3.
ZnO monocrystal
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※ Powder Preparation
Crystal grain integrated； Radius is small and distribute uniformly； Few cluster；
(2) Powder preparation
Can get the chemical stoichiometric substance and needed topograph； Can use more cheap raw materials. High temperature and ball milling are avoided, which can prevent the impurity and defects.
BaTiO3), however, they can not be prepared
by other methods.
※ Fluid effect of melt
4-inch LiNbO3 Si single crystal
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auto pulling technique
1. feeder 2. growth chamber
3. crucible
4. bottom heater 5. gas valve 6. melt-level regulator 7. probe
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坩埚下降法
Crystal furnace with a cooling stick
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3) zone melting method
• Strait heater move along the polycrystal raw material stick
• Melt---cool---single crystal stick
Disadvantages:
• Lattice match should less than 1%. The thickness is large for the quick rate, it is difficult to get nano film. The surface topograph is worse than that of vapor phase epitaxy.
Pt, Ir, Pt/Rh
GaAs, oxide
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Factors influence the quality of crystal：??
※ Temperature gradient on solid-liquid interface ※ Growth rate
※ Crystal spin rate
How to? • principle：make the solution in a metastable state and a certain supersaturation by control the cooling rate. • Key points for single crystal growth: avoid the 26 microcrystal; control the temperature strictly.
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3) High-temperature solution growth method (melt salt method)
• Use liquid metal or melt inorganic compound as solvent, form uniform saturated solution in high temperature. • Constant solvent： – Liquid metal – Liquid Ga（dissolve As） – Pb, Sn or Zn（dissolve S, Ge, GaAs） – KF（dissolve BaTiO3） – Na2B4O7（ dissolve Fe2O3）