We report the growth and characterization of the AlGaN on low temperature (LT) AlN interlayer (IL) and effect of AlN IL on incorporation efficiency of Al composition in the AlGaN. The AlGaN layers were grown on AlN ILs by metalorganic vapor phase epitaxy (MOVPE) and characterized by X-ray diffraction (XRD) and MeV He ion Rutherford backscattering spectrometry (RBS) and cathodoluminescence (CL), the results indicate that introduction of double AlN IL resulted in an increase in Al composition incorporation efficiency. (c) 2006 Elsevier B.V. All rights reserved.