GaN nanocolumns were first self-assembled by rf-plasma molecular beam epitaxy (rf-MBE) in 19971) and were applied for the fabrication of visible 2, 3) to ultraviolet 4) nanocolumn LEDs on Si, by integrating the InGaN/GaN multiple quantum wells (MQWs) in those. In the self-assembled nanocolumn LEDs, however, the diameter and position of nanocolumns were randomly deviated, frequently resulting in multi-color spot emissions 3). To improve such randomness, we developed Ti-mask selective area growth (SAG) of GaN nanocolumns5, 6) fabricating orderly arrayed triangular lattice GaN nanocolumns. By growing high In-content InGaN on the GaN nanocolumn arrays, near infrared (1.46 μm) nanocolumn LEDs 7) have been demonstrated. The emission color of InGaN-based nanocolumn arrays shifted from blue to red with increasing the nanocolumn diameter 8). Using the finding, the monolithic integration of InGaN-based LEDs with different emission colors has been demonstrated 9). Orange emitting nanocolumn arrays 10) have exhibited high internal-quantum-efficiencies and red-emitting nanocolumn LEDs have been fabricated 11).