Formation of a Compact Layer and Its Influence on the Optical Propertiesof GaN Nanorods Grown on Si Substrates

Abstract

GaN nanorods were grown on Si(111) substrates by using molecular beam epitaxy. Between the substrates and the GaN nanorods, compact layers were often formed. We compared the photoluminescence (PL) spectra for samples with and without compact layers. The PL spectra from the GaN nanorods without compact layers revealed a doublet at 3.442 eV and 3.448 eV. A PL peak at 3.41 eV, often observed from GaN nanorods with compact layers, was also observed from the backside PL spectra of high-quality GaN epilayers grown on sapphire substrates, indicating that the PL peak was associated with an interfacial structural defect. Comparison of the PL peak energies of the nanowires with those of the bulk GaN indicates that the nanorods are fully relaxed.