We report on the state-of-the-art parameters of GaN PA MBE layers grown on GaN/c-Al2O3 MOVPE templates and compare the structural and optical properties of InxGa1-xN layers grown under different conditions on top of the GaN-MBE/GaN-MOVPE/Al2O3 buffer structures. Atomically smooth and structurally perfect GaN and In0.14Ga0.86N epilayers have been achieved. The relatively low values of indium incorporation efficiency alpha(In) in the InGaN layers grown on templates limits the maximum growth temperature and In-content that are necessary to achieve bright RT luminescence in the long-wavelength spectral range (> 500 nm). It has been proposed that implementation of N-rich growth conditions resulting in the nanocolumnar growth morphology increases alpha(In) and facilitates inhomogeneous spatial distribution of In in InGaN alloys, which play a crucial role in the red shift of the RT luminescence up to 510 nm and enhancement of its intensity. (c) 2006 Elsevier B.V. All rights reserved.