Significant improvement in the structural and optical qualities of GaN thin films on sapphire substrates was achieved by metal organic chemical vapor deposition with an in situ SiNx nanonetwork. Transmission electron microscope studies revealed that screw- and edge-type dislocations were reduced to 4.4 x 107 and 1.7 x 107/cm2, respectively, for a ~5.5µm-thick layer. Furthermore, room temperature carrier lifetimes of 2.22 and 2.49ns were measured by time-resolved photoluminescence for samples containing single and double SiNx network layers, respectively, representing a significant improvement over the previous studies. The consistent trends among the transmission electron microscopy, X-ray diffraction, and time-resolved photoluminescence measurements suggest that in situ SiNx network reduces line defects effectively as well as the point-defect-related non-radiative centres.

Low Dislocation Densities and Long Carrier Lifetimes in GaN Thin Films Grown on a SiNx Nanonetwork. J.Xie, Ü.Özgür, Y.Fu, X.Ni, H.Morkoç, C.K.Inoki, T.S.Kuan, J.V.Foreman, H.O.Everitt: Applied Physics Letters, 2007, 90[4], 041107