Polarity control and preparation of AlN nano‐islands by hydride vapor phase epitaxy

Initial growth condition of AlN on sapphire substrate by HVPE was investigated. It was found that polarity of AlN was significantly affected by temperature even under the condition of AlCl3 pre‐flow and that polarity was drastically changed from N‐polarity to Al‐polarity with increasing temperature around 1000 °C. Polarity of AlN was easily controlled by growth temperature. By utilizing these findings and etching technique by alkaline solution, AlN nano‐islands were successfully obtained on sapphire substrates. AlN nano‐islands had mixture of trapezoid and column structure with 100 nm or less in diameter. Also it had epitaxial relation to sapphire substrates. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)