InxAl1-xN nanocolumns (x(1n) = 0.73-1.00) of c-axis orientation were successfully self-organized on Si (111) substrates by RF-plasma-assisted molecular-beam epitaxy (RF-MBE). The height, diameter and density of nanocolumns were 0.7-1.1 m, 40-130 nm, and 0.7-3.0 x 10(10)cm(-2), respectively. With increasing In composition from 0.73 to 1.00, the room-temperature photoluminescence (RT-PL) peak wavelengths shifted from 1.06 to 1.87 mu m. AlN nanocolumns (when x(In) = 0) were also fabricated, and RT-PL was observed with a peak energy of 5.85 eV. (c) 2006 Elsevier B.V. All rights reserved.