Optical characteristics of multiple layered InGaN quantum wells on GaN nanowalls grown on Si (111) substrate

•GaN nanowall crystals were grown on Si substrate using MBE.•In the low N/Ga flux ratio, GaN nanopillars and nanowalls were mixed.•The InGaN MQWs were formed on the various N/Ga flux ratios of GaN nanowalls.•The PL emissions originated from the InGaN MQWs were observed.•Intensity ratio at room temperature and 8 K increased as deceasing N/Ga ratio.

GaN nanowall crystals and InGaN multiple quantum wells (MQWs) were grown on Si (111) substrate using molecular beam epitaxy. In high N/Ga flux ratio, dense two dimensional network GaN nanowall structures were grown with small pores. The continuity of GaN nanowall structures was decreased as decreasing the N/Ga flux ratio. In the N/Ga flux ratio of 50, nanopillars and nanowalls were mixed. The InGaN MQWs were formed on the GaN nanowall crystals which were grown in the various N/Ga flux ratios. The strong photoluminescence originated from the InGaN MQWs on GaN nanowall crystals around a wavelength of 400 nm was observed at the temperatures from 8 K to 300 K (room temperature). The ratios of the photoluminescence intensities at 8 K and the room temperature were measured for the InGaN MQWs. The higher ratio was obtained as decreasing the N/Ga flux ratio of the GaN nanowall crystal growth.

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