To improve crystal quality of InN, an in-situ cyclic rapid pulse annealing during growth was carried out using infrared-lamp-heated molecular beam epitaxy. A cycle of 4 min growth of InN at 400 degrees C and 3 s pulse annealing at a higher temperature was repeated 15 times on AlN on Si substrate. Annealing temperatures were 550, 590, 620, and 660 degrees C. The back of Si was directly heated by lamp irradiation through a quartz rod. A total InN film thickness was about 200 nm. With increasing annealing temperature up to 620 degrees C, crystal grain size by scanning electron microscope showed a tendency to increase, while widths of X-ray diffraction rocking curve of (0 0 0 2) reflection and E-2 (high) mode peak of Raman scattering spectra decreased. A peak of In (1 0 1) appeared in X-ray diffraction by annealing higher than 590 degrees C, and In droplets were found on the surface by annealing at 660 degrees C. (C) 2009 Published by Elsevier B.V.