High efficiency green, yellow, and amber emission from InGaN/GaN dot-in-a-wire heterostructures on Si(111)

The authors report on the achievement of nearly defect-free, vertically aligned InGaN/GaN dot-in-a-wire nanoscale heterostructures grown directly on Si(111) substrates by molecular beam epitaxy. Strong green, yellow, and amber emission, with a room temperature internal quantum efficiency of ∼45% of that measured at low temperature (∼10 K), was achieved. Detailed structural and optical studies further confirm that the emission characteristics are strongly influenced by the presence of In-rich nanoclusters, formed by phase segregation, in the InGaN dots.