Growth of InGaN/GaN core–shell structures on selectively etched GaN rods by molecular beam epitaxy

• Ordered growth of InGaN/GaN core–shell structures by molecular beam epitaxy.
• Study the In incorporation depending on growth conditions.
• STEM–CL measurement of InGaN/GaN core–shell.
• Study of morphology evolution of the InGaN/GaN structure during overgrowth.

This work reports on the growth and characterization of InGaN/GaN core–shell structures by plasma-assisted molecular beam epitaxy on an ordered array of top-down patterned GaN microrods fabricated on a GaN/sapphire substrate. Growth of InGaN/GaN is conformal, with axial and radial growth components leading to core–shell structures with clear hexagonal facets. The radial InGaN growth (shell) was confirmed by spatially resolved cathodoluminescence performed using scanning electron microscopy as well as scanning transmission electron microscopy. The In content of the InGaN shell is controlled by means of the growth temperature and the III/V ratio.