A comparison of dislocation densities in AlGaN and InAlGaN with approximately similar alloy compositions was completed. A systematic series of the AlGaN layers with a concentration of 17%Al were grown by metal-organic chemical vapor deposition with trace amounts of indium incorporated into the layers. X-ray diffraction analysis by Williamson Hall plot and reciprocal space mapping was employed to investigate columnar structure in these layers. It was found that lateral coherence length, related to threading dislocation, was systematically varied with Indium content. The lateral coherence length increased with the consequence that the threading dislocation density decreased as Indium content increased, which indicated that even small amounts of indium incorporation could improve crystalline quality. The results were in good agreement with etch pit density study using AFM.

Effects of Indium Incorporation in AlGaN on Threading Dislocation Density. H.Kang, S.Kandoor, S.Gupta, I.Ferguson, S.P.Guo, M.Pophristic: Physica Status Solidi C, 2005, 2[7], 2145-8