Investigation of the structural defects in GaN thin films grown by organometallic vapor phase epitaxy

Abstract

GaN thin films were prepared on {0001} planes of sapphire substrates by organometallic vapor phase epitaxy (OMVPE) techniques. The crystall orgaphic relation between the film and the substrate as well as the structural features of the defects in the film were investigated by transmission electron microscopy (TEM). Epitaxial relationship was observed in the GaN/sapphire heterostructure preparedin this investigation; (0001) GaN//(0001) sapphire;$\left[ {01\bar 10} \right] GaN//\left[ {\bar 12\bar 10} \right]$ sapphire. Dislocations of Burgers vector$\bar b = {1 \mathord{\left/ {\vphantom {1 3}} \right. \kern-\nulldelimiterspace} 3}\left[ {2\bar 1\bar 10} \right]$ were observed in the film; the propagation behavior of the dislocations exhibits a slip system$\left\{ {10\bar 10} \right\}\left\langle {2\bar 1\bar 10} \right\rangle$ is operative in the film. Inversion domain boundary (IDB) facets lying parallel to$\left\{ {01\bar 10} \right\}$ and$\left\{ {\bar 12\bar 10} \right\}$ planes were observed; the type of anti-site bonds (Ga-Ga, N-N) is altemate along these IDB planes, kee** the simple stoichiometry of the compound.