N-TYPE CONDUCTIVE ALUMINUM NITRIDE SEMICONDUCTOR CRYSTAL AND METHOD FOR PRODUCING THE SAME

摘要

After forming an AlN crystal layer on a single crystal substrate such as a sapphire substrate by HVPE, the substrate temperature is raised to 1,200°C or higher and a layer composed of an n-type conductive aluminum nitride semiconductor crystal is rapidly formed thereon by HVPE, thereby obtaining a laminate. The n-type conductive aluminum nitride semiconductor crystal layer contains from 1 OE10¹⁸ to 5 OE10²⁰ cm^-3 of Siatoms, while containing substantially no halogen atoms, and does not substantially absorb light having an energy of not more than 5.9 eV. Then, the n-type conductive aluminum nitride semiconductor crystal layer is separated from the thus-obtained laminate, thereby obtaining a self-supporting substrate. Consequently, there is produced a self-supporting substrate composed of an n-type conductive aluminum nitride semiconductor crystal, which is useful for manufacturing a vertical conduction AlN semiconductor device.