Aluminum nitride (or AlN) is a nontoxic, high-insulating and highly thermally conducting material that can be produced with very little energy. It is able to withstand very high temperatures and resists the penetration of most halogen gases, making it an ideal material for process environments such as those encountered in semiconductor equipment and RF plasma. It is also nonflammable and chemically stable, which makes it a useful sealing material for electronic devices.
It is a white or off-white, dense and solid material. It is covalently bonded and has a hexagonal wurtzite crystal structure. AlN can be made from the carbothermal reduction of aluminum oxide in gaseous nitrogen or by direct nitridation of aluminum metal. The use of sintering aids and hot pressing is required to produce a dense technical grade of the material. AlN is soluble in mineral acids via attack on the grain boundaries and granular material, but is insoluble in strong alkalis and decomposes slowly in water.
AlN exhibits the wide band gap characteristic of III-V group semiconductor materials. It has a theoretical energy gap of 6.2 eV. When doped, it can be used for a variety of light-emitting diode applications such as blue and ultraviolet. It is also a good substrate material because it can withstand very high temperatures and has excellent electrical properties. AlN can replace silicon and gallium nitride in many applications where high temperature resistance, wide band gap and low cost are required.