Morphological Control of InN Nanorods by Selective Area Growth–Hydride Vapor-Phase Epitaxy

Control over the morphology of InN nanorods, which remains challenging due to the complex mechanisms involved in the growth process, is essential for the next generation of nano- and optoelectronic devices. In this paper, we report on the selective area growth (SAG) of InN nanorods on Ga-polar GaN/cAl(2)O(3) templates using hydride vapor-phase epitaxy (HVPE). A systematic study of the evolution of the shape of InN nanorods under various growth conditions-growth temperature, growth time, and the input NH3 partial pressure-is carried out. The optimal growth temperature to achieve a perfect selectivity and prevent InN decomposition is first determined. The dependence of the axial and radial growth rates on the growth temperature and vapor phase composition with group V elements is discussed. The influence of mass transport on the InN nanorods' geometry is shown to be more pronounced at extended growth times. Swapping of the nanorods' morphology from pencil to a perfect hexagonal shape is controlled by varying the growth time. Photoluminescence measurements on InN nanorods are interpreted by considering a concentration of free electrons. The results reported herein provide relevant information for understanding SAG of InN and could pave the way to develop high-performance InN nanorods-based devices.