The insertion of Al0.06Ga0.94N/GaN strained-layer superlattice cladding underlayers into InGaN-based multi-quantum well structures grown onto Si(111) substrates with an AlN/GaN intermediate layer was investigated. The Al0.06Ga0.94N/GaN strained-layer superlattice underlayer improved emission wavelength uniformity and led to a narrower emission full-width at half-maximum than that for a conventional GaN underlayer. Gaussian fitting was applied to photoluminescence spectra in order to study the emission wavelength behaviour and integrated intensity of the peak energy. A higher (29.4%) multi-quantum well internal quantum efficiency was obtained for samples with Al0.06Ga0.94N/GaN strained-layer superlattice underlayers than that (20.6%) for GaN underlayers. Transmission electron microscopy indicated that the Al0.06Ga0.94N/GaN strained-layer superlattice layer sharply bent threading dislocation lines; thus reducing the threading dislocation density in the multi-quantum well. Reciprocal space mapping results suggested that compressive strain in the GaN portion of the Al0.06Ga0.94N/GaN strained-layer superlattice produced the sharp inclination of the threading dislocations.

Effect of Al0.06Ga0.94N/GaN Strained-Layer Superlattices Cladding Underlayer to InGaN-Based Multi-Quantum Well Grown on Si(111) Substrate with AlN/GaN Intermediate Layer. B.A.B.A.Shuhaimi, A.Watanabe, T.Egawa: Japanese Journal of Applied Physics, 2010, 49[2], 021002