Optical properties of serrated GaN nanowires

Abstract

GaN nanowires with periodic serrated morphology have been synthesized on Si substrate by Au-catalyzed vapor-liquid-solid growth mode. The presence of Mn vapor during growth process has been found to enhance the production and quality of serrated GaN nanowires, without introducing dopants. We have performed photoluminescence and Raman spectral measurements on nanowires with different levels of serration. Temperature dependent photoluminescence revealed a broad yellow-green and red luminescence in the samples. Room temperature Raman spectra exhibits disorder-activated phonon mode at ~670 cm−1, in addition to E2(high) and A1(LO) modes of GaN. Further investigation of Raman spectra revealed the presence of tensile stress in the GaN nanowires when Mn vapor is present during the growth process. The dependence of the optical properties on the morphology of GaN nanowires shows that they can be tuned by initial synthesis conditions.