Growth of Ill-nitride quantum dots and their applications to blue-green LEDs

In this paper we discuss the growth of InN, GaN and InGaN QDs by MBE on either GaN or AlN templates. InN QDs on GaN templates were found to occur without an InN wetting layer, a result consistent with the large lattice mismatch of 11% between InN and GaN. Self-assembled GaN QDs were grown on AlN templates, using the modified Stranski-Krastanov mode of growth. The microstructure and the size distribution of such QDs in a single layer or a superlattice structure were investigated by electron microscopy and atomic force microscopy. Finally, the self assembly of InGaN QDs on GaN templates using the Stranski-Krastanov mode and the applications of such QDs to blue-green LEDs are addressed. The results indicate that InGaN / GaN multiple quantum dots (MQDs) are highly strained and their emission at low injection is red shifted with respect to that of a single layer of QDs due to quantum confined Stark effect.