A growth method, named droplet elimination by radical-beam irradiation (DERI), consisting of a metal-rich growth process (MRGP) and a droplet elimination process (DEP), was developed for the growth of InGaN ternary alloys. In the MRGP using the growth of InGaN under a metal-rich condition [N*/(In+Ga)<1], Ga was preferentially incorporated into the growing InGaN and In was forced out to the surface. This In was transformed to epitaxial InN on top of the InGaN underlayer in the DEP using a subsequent nitrogen radical-beam irradiation. By repeating the MRGP and DEP, an InN/InGaN periodic structure was successfully fabricated.