Growth of free-standing GaN layer on Si(1 1 1) substrate

Abstract

This investigation demonstrates the epitaxial growth of a free-standing GaN layer on Si(1 1 1) using a funnel-like GaN nano-rod buffer structure. The funnel-like GaN nano-rods were directly grown on Si substrates by RF-plasma molecular beam epitaxy. Free-standing GaN layers were achieved through the coalescence of funnel-like GaN nano-rods by the metalorganic chemical vapor deposition. This study examines the structure, optical characteristics and stress of GaN nano-rods and free-standing GaN layers. The c-axis lattice constant of the strain-free Ga-face GaN layer on Si is 5.1844 Å, as determined by high-resolution X-ray diffraction. The fully relaxed band edge at 3.468 eV without deep-level emission around 2.3 eV, was revealed in a free-standing GaN layer on Si, using photoluminescence.