ABSTRACT
This chapter reviews studies on Gallium nitride (GaN)-based nanocolumns performed at Sophia University are systematically. It addresses the first self-organization of nanocolumns, visible-light-emitting InGaN-based nanocolumns, and the nanocrystal effects of such nanocolumns, controlled growth of regularly arranged nanocolumns by molecular beam epitaxy (MBE), and application of GaN nanocolumns to nanocolumn light emitters. GaN nanocolumns, which are one-dimensional nanocrystals with diameters of less than several hundred nanometers, have been self-organized by radio-frequency-plasma-assisted MBE and subsequently extensively studied. Nanocolumn light-emitting diodes consist of a huge number of GaN-based nanocolumns, spontaneously nucleated during their self-organization. A technique for selective-area growth of nanocolumns on GaN templates has been developed to achieve precise control in the size and position of nanocolumns, resulting in uniform arrays of GaN nanocolumns. GaN nanocolumn templates with heights of 150–200 nm were employed to enhance the nucleation of Aluminium GaN nanocrystals on them, which was essential to forming the nanocolumn structure of the Aluminium GaN.
