The controlled growth of GaN microrods on Si(111) substrates by MOCVD

•Selective area growth (SAG) of GaN microrods on SiNx/Si(111) templates is investigated.•Optimized time for filling the mask openings is necessary in terms of structure morphology—semipolar facets development.•Absence of silane during the growth not only inhibits the vertical growth of the microrods but also decreases the crystal quality.•Raman scattering revealed nearly strain-free GaN microrods of crystal quality comparable to bulk crystals.

In this paper, a selective area growth (SAG) approach for growing GaN microrods on patterned SiNx/Si(111) substrates by metal-organic chemical vapor deposition (MOCVD) is studied. The surface morphology, optical and structural properties of vertical GaN microrods terminated by pyramidal shaped facets (six {101¯1} planes) were characterized using scanning electron microscopy (SEM), room temperature photoluminescence (PL) and Raman spectroscopy, respectively. Measurements revealed high-quality GaN microcolumns grown with silane support. Characterized structures were grown nearly strain-free (central frequency of Raman peak of 567±1 cm−1) with crystal quality comparable to bulk crystals (FWHM=4.2±1 cm−1). Such GaN microrods might be used as a next-generation device concept for solid-state lighting (SSL) applications by realizing core-shell InGaN/GaN multi-quantum wells (MQWs) on the n-GaN rod base.