The influence of intermediate AlN/GaN, AlGaN/GaN or AlN/AlGaN strained multilayer structures upon the threading dislocation density and optical properties of GaN films was studied. A series of GaN films were deposited at 1050C onto (00▪1) sapphire substrates by using intermediate AlN/GaN, AlGaN/GaN or AlN/AlGaN strained multilayer structures. Etch-pit density counts and transmission electron microscopic studies showed that the implementation of AlN/GaN and AlGaN/GaN in GaN films enables the blocking of threading dislocations in the films very efficiently. Photoluminescence measurements exhibit the increment of near band edge emission intensity in the GaN films having Al0.5Ga0.5N/GaN or AlN/GaN intermediate strained multilayer structures. Cross-sectional transmission electron microscopic observations showed that threading dislocation annihilation and de-multiplication processes played important roles in the threading dislocation density reduction in the GaN films having Al-containing strained multilayer structures.

Effects of Al-Containing Intermediate III-Nitride Strained Multilayers on the Threading Dislocation Density and Optical Properties of GaN Films. J.R.Gong, S.F.Tseng, C.W.Huang, Y.L.Tsai, W.T.Liao, C.L.Wang, B.H.Shi, T.Y.Lin: Japanese Journal of Applied Physics-1, 2003, 42[11], 6823-6