Sublimation growth of aluminum nitride crystals

The crystal growth of AlN unseeded on a tungsten crucible lid and seeded on a polycrystalline AlN wafer is compared. AlN crystals with a preferential (0 0 0 1) orientation were achieved in both methods, as demonstrated by electron backscattering diffraction. The AlN grain size increased with the thickness of the AlN crystals. Seeded growth produced larger grains than unseeded growth (average grain size of less than 500 μm compared to 2–3 mm). Photoluminescence confirmed the high quality of the resultant AlN crystals.