THE EFFECT OF GEOMETRICAL MISFIT DISLOCATION ON FORMATION OF MICROSTRUCTURE AND PHOTOLUMINESCENCE OF WURTZITE GAN AL2O3 (0001) FILMS GROWN BY LOW-PRESSURE METAL-ORGANIC CHEMICAL-VAPOR-DEPOSITION/

The incoherent GaN/sapphire interface and microstructure of GaN were o bserved by high resolution transmission electron microscopy. The most mobile 600 mixed-type dislocation is related to a structural metastabi lity of the Wurtzite GaN film. In spite of the same feature of interba nd absorption, the photoluminescence mechanism is sensitive to deep le vel. A strong light emission from the bound exciton of Wurtzite GaN at 358 nm was observed in an n-type GaN sample with the GaN buffer layer . The donor-acceptor pair recombination at 380 nm with LO phonon repli cas at 390 and 403 nm and the deep level at 559 nm a ere observed in b oth an undoped GaN sample with GaN buffer layer and an n-type GaN samp le with AIN buffer layer. This optical behavior is sensitive to the Si doping and the type of buffer layer materials. The deep level emissio n along the dislocation line is suggested by the local band bending mo del providing the potential barrier of 0.63 eV by the space charge. PA CS numbers: 61.72.Ff, 78.66.Fd, 64.80.Gd, 71.25.Tn. (C) 1998 Elsevier Science S.A. All rights reserved.