AlN growth technology
AlN crystal
Bulk AlN crystals are most successfully grown by a sublimation-recondensation process (PVT growth) at temperatures exceeding 2000°C. A set-up based on tungsten parts is most stable against the aggressive vapor and provides very low contamination of the growing crystal, which results in UV-transparent wafers.
Large-area AlN single crystals are obtained by seeding on silicon carbide (SiC) substrates and continuously regrowing on pure aluminum nitride wafers. Thus it is possible to follow the SiC seed size in the resulting AlN crystals. CrystAl-N's patented growth technology can follow the size of any SiC seed with roughly one inch less in diameter, which leads to a unique competitive advantage:
UV-transparent wafers in large diameters with high upscaling potential.
Fabricated AlN wafers resulting from this growth process are well-defined in orientation and of the highest UV-transparency available on the market, which is inevitable to produce UV LEDs.
Material properties
Crystal structure
Lattice constants
Thermal conductivity
Acoustic wave velocity*
Band gap (293 K)
Dielectric constant
Piezoelectric constant*
Wurtzite P63mc
a = 3.112 Å; c = 4.982 Å
3.23 g/cm3
285 W/mK
11300 m/s
6.0 eV (direct)
1.56 C/m2
* measured along (0001) direction (v33 or e33)
AlN does not melt but rather dissociates at approx. 2400°C: Crystal growth from the gas phase!
Polished Surface c-plane
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Polished Surface m-plane
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AlN in the value chain
The quality of the substrate determines strongly the performance of electronic devices. Due to the inherent physical and chemical properties of AlN, the lattices of the epitaxial layers and the substrate are of higher/improved/better compatibility between each other. Thus, fewer epitaxial buffer-layers are needed, which reduces process cost significantly.
AlN in the value chain
Existing devices strongly benefit from aluminum nitride. Furthermore, totally new products are possible due to the bandgap at 6.1 eV. Especially in the field of UV-LEDs.
LED expl. 1
As many regions in the world are suffering from a lack of clean water, there is an unavoidable necessity for suitable point of use sterilization systems.
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LED expl. 1
Converting electricity from one voltage to another, applications for power conversion devices are part of everybody's life, like power adapters, solar cell plants or PCs.
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