Seeded growth of AlN single crystals by physical vapor transport

Seeded growth of AlN single crystals was achieved in an induction-heated, high-temperature reactor. The growth process was based on physical vapor transport (PVT), where presintered AlN powder was used as source material. AlN seeds were cut from a boule containing large single crystalline grains, which were grown by natural grain expansion of an initially polycrystalline, self-seeded deposit. Seeded growth was interrupted several times in order to refill the AlN powder source and a dedicated pro cess scheme was used to ensure epitaxial re-growth on the seed surface after each exposure to air. The single crystalline seed expanded laterally at an angle of 45 degrees resulting in an 18 min large AlN single crystal. The crystal expansion rate, crystalline orientation, as well as growth morphology were characterized by optical microscopy and X-ray diffraction, respectively. (c) 2005 Elsevier B.V. All rights reserved.