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.