The interfacial structure and extended defects in a-plane (11•0)-oriented GaN

layers were investigated using conventional and high resolution transmission

electron microscopy. The a-plane GaN epilayers were grown by nitrogen rf plasma

source molecular beam epitaxy onto r-plane sapphire substrates, which were

nitrided either at 200 or at 800C for 1h. A thin interfacial layer of strained AlN,

with an average thickness of about 1nm, was formed during nitridation of the

sapphire surface at both temperatures. The extended defects observed in the GaN

layers were predominantly threading dislocations and basal stacking faults, which

originate from the GaN/sapphire interface. The threading dislocation density was

slightly reduced in the film nitrided at 800C, as was the density of inversion

domains, although stacking fault density does not appear to change with nitridation

conditions.

Electron Microscopy Investigation of Extended Defects in a-Plane Gallium Nitride

Layers Grown on r-Plane Sapphire by Molecular Beam Epitaxy. J.Smalc-

Koziorowska, P.Komninou, S.L.Sahonta, J.Kioseoglou, G.Tsiakatouras,

A.Georgakilas: Physica Status Solidi C, 2008, 5[12], 3748-51