zincite properties. growth methods. applications. zno kortunova e.v., dubovskiy a.b., filippov i.m.,...
TRANSCRIPT
ZinciteProperties. Growth
methods. Applications.
ZnO
Kortunova E.V., Dubovskiy A.B., Filippov I.M., Kaurova I.A.
- Mineral Ltd.
1, Institutskaya st., Alexandrov, Vladimir Region 601650, Russia
Applications of ZnO crystals
High quality crystal substrates
Luminescence devices
Electronic components
Piezoelectronic devices
Acoustoelectronics
for ZnO heteroepitaxy
for optical waveguides
Phosphorscintillators
Light emitting diodes and semiconductor lasers for UV spectrum
Varistors
High-temperature diodes, transistors Ultraviolet photoconverters
Ultrasonic emitters, receivers
Piezoelectric transducers
Piezoresonance components
Discrete SAW-components, convolvers
Surface acoustic wave filters and resonators
Radiofrequency markers
ZnO structure
(11-20) projection (0001) projection
Structural prototype – WurtziteHexagonal syngony
Space group P63mc
Lattice parameters :а=3,2495 А, с=5,2069 А
Density – 5,64 ± 0,01 g /cm3
Melting point – 1975 °С
Temperature of phase transition – 1870°С
Thermal conductivity – 49,1 W/m · К
Hardness – 4 (by Mohs scale)
Width of district zone (bandgap) – 3.44 eV
Specific resistivity – 0,1..1 · 1013 Om·cm
Mobility of carriers –180 cm2/V · s
ZnO main properties
Elastic constant
с11 - 209,718 GPa; s11 - 7.858 TPa-1
с12 - 121,14 GPa; s12 - -3.432 TPa-1
с13 - 105,13 GPa; s13 - -2.206 TPa-1
с33 - 210,941 GPa; s33 - 6.94 TPa-1
с44 - 42,449 GPa; s44 - 23.57 TPa-1
с66 - 44,289 GPa; s66 - 22.58 TPa-1
Permittivity
11s/0 – 8.33 33
s/0 – 8.8 11
t/0 – 9.26 33t/0 – 11.0
Piezomodule
d15 - -13.9*10-12 Cl/N; d31 - -5,2*10-12 Cl/N; d33 - 10,6*10-12 Cl/N
Optical parameters
Refraction index wave-length, mkm n0 ne
0,45 2,105 2,123 0,5 2,051 2,068 0,8 1,959 1,975 1,4 1,9298 1,943 1,8 1,923 1,937 2,6 1,913 1,927 3,4 1,902 1,916 4,0 1,889 1,907
Growth methods of ZnO
Growth from solution in
melt
Growth by hydrothermal
method
Growth from gas phase
Growing ZnO single crystals from solution in melt
Solubility of ZnO in PbF2 melt. Grower diagram
mm/daymole %
Growing ZnO single crystals by gas-transporting reactions method
Hydrothermal method to obtain ZnO single crystals of large size
1. body of autoclave,2. lining,3. insert, 4. insert cover, 5. frame for seed
suspension, 6. charge, 7. baffle, 8. thermocouple, 9. steel sealing ring, 10. hole in steel ring,11. steel ring, 12. flange,13. flange, 14. obturator, 15. bolt, 16. nut.
• Working solution: mixture
4М(КОН) + 1М(LiOH) + 0.1M(NH4OH)
• Seeds: ZnO monoherdal or prism
orientation
• Size ~ 80 mm
• Cycle duration ~ 180 days
• Working temperature ~ 300-350 ºС
• Pressure ~ 500 atm.
• Temperature gradient between growth
and dissolution chambers 8-15 ºС.
• Thickness of crystals 25-30 mm
Hydrothermal synthesis
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3
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Schematic drawing of hydrothermal growth system.
1. Pressure metering system; 2. channel for thermocouples; 3. autoclave lid; 4. autoclave; 5. liner; 6.container with frames ; 7. internal baffle;8. basket with the nutrient; 9. heaters of crystallization zone;10. external heater of dissolution zone; 10. internal heater of dissolution zone.
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Zinc oxide crystals grown in an industrialautoclave.а) the smallest frame of container;b) single crystal ZnO.
The growth rate of (0001) –0.05 - 0.11 mm/day.
The growth rate of (10-10) –0.02 – 0.05 mm/day.
а)
b)
Results of experiment
Dependency of zinc solubility from temperature
Hydrothermal methodDependency of zinc solubility
from KOH and NaOH concentration
mass %mass %
mass %
Dependency of growth rate of positive monohedron from temperature
Hydrothermal synthesis
1 – at temperature gradient 75 ºС
2 – at temperature gradient 50ºС
1 – according to calculation data
2 – according to experimental data
mm/daymm/day
Dependency of face (0001) growth rate from temperature gradient ∆Т at different concentration of LiOH
Hydrothermal synthesis
1 - without LiOH
2 – 1.0М LiOH
3 – 2.0М LiOH
4 – 3.0 М LiOH
mm/day
Electrophysical parameters
Transmission range Spectrum of photoluminescenceLaser excitation 325,0 nm, 3,5 mW
Conclusions:1. Provided optimal conditions for hydrothermal growth it is
possible to obtain high-quality ZnO single crystals. Furthermore, big size crystals (over 50 mm) can be grown while the main problem is absence of large seed material.
2. Hydrothermal technology allows to dope zinc oxide crystals with required admixtures.
3. On the basis of homogenious high-quality ZnO single crystals it is possible to design fast scintillators, effective high-frequency piezotransducers, acoustoelectronic devices, high-temperature sensors, elements of power high-temperature electronics. However, the major application of ZnO crystals will be the use as substrates for ZnO homoepitaxy to create optoelectronic devices.