Evolution of GaN nanoflowers from AlN–SiO2 grains on a silicon substrate by chemical vapor reaction

Gallium nitride (GaN) nanoflowers were synthesized on a silicon (Si) substrate at growth temperatures of 650 and 600 °C and under HCl:NH3 flow ratios of 1:20, 1:30, and 1:40 by hydride vapor phase epitaxy. Numerous nanorod and nanoneedle burs were formed within each nanoflower. The nanoflower size increased with increasing NH3 gas flow rate. The nanoflower formation mechanism is proposed based on cross-sectional scanning electron microscopy images and bright field image of scanning transmission electron microscopy. Nanoflowers were evolved from irregular regions with AlN–SiO2 grains on a Si substrate, i.e., the roughness of substrate affects nanoflower formation by causing nanoburs to protrude, exposing them to higher gas concentrations.

► We report on the synthesis of GaN nanoflowers. ► We describe the growth mechanism of GaN nanorod and nanoneedle flowers. ► The cross-sectional images of TEM and SEM showed that the nanoflowers are originated from the AlN layer with SiO2 grain. ► The results will contribute to the study of nanostructures.