The temperature dependence of InN growth on (0001) sapphire substrates by atmospheric pressure hydride vapor phase epitaxy (HVPE) was investigated. N-polarity single-crystal InN layers were successfully grown at temperatures ranging from 400 to 500 °C. The a and c lattice constants of InN layers grown at 450 °C or below were slightly larger than those of InN layers grown above 450 °C due to oxygen incorporation that also increased the carrier concentration. The optical absorption edge of the InN layer decreased from above 2.0 to 0.76 eV when the growth temperature was increased from 450 to 500 °C. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)