Chapter Seven – Selective Area Growth of InGaN/GaN Nanocolumnar Heterostructures by Plasma-Assisted Molecular Beam Epitaxy

Abstract The aim of this work is to gain insight into the selective area growth (SAG) of InGaN nanostructures by plasma-assisted molecular beam epitaxy, focusing on their potential as building blocks for next-generation LEDs. Several nanocolumn (NC)-based approaches such as standard axial InGaN/GaN structures and InGaN/GaN core–shell structures are discussed. The first section reports on the growth and characterization of ordered InGaN NCs as well as light-emitting diodes grown on c -plane GaN/sapphire templates. In particular, the growth mechanism of green-emitting InGaN/GaN NCs is discussed. In order to enable white light emission the stacking of red, green, and blue emitting segments is used to achieve the monolithic integration of these structures in one single InGaN NC allowing for the fabrication of ordered broad spectrum emitters. As alternative to axial InGaN/GaN nanostructures, the next section reports on the growth and characterization of InGaN/GaN core–shell structures with emission at around 3.0 eV. Furthermore, the successful fabrication of a core–shell pin diode structure is demonstrated. Finally, the SAG of In(Ga)N/GaN NCs on Si(111) substrates is presented. Ordered In(Ga)N/GaN NCs emitting from ultraviolet (3.2 eV) to infrared (0.78 eV) were grown on top of GaN-buffered Si substrates.