A structural investigation of highly ordered catalyst- and mask-free GaN nanorods.
GaN nanorods were grown on r-plane sapphire substrates by a two-step approach. Nucleation sites for the nanorods were provided by the formation of AlN islands during nitridation in a metal organic vapor phase system. These islands are a-plane oriented as expected for nitride growth on r-plane sapphire. The nanorods themselves were grown by plasma assisted molecular beam epitaxy. The nanorods show an inclination towards the surface normal of 28.3° and are highly ordered. Studies with high resolution x-ray diffraction polar plots reveal the epitaxial relationship between the substrate and nanorods as a c-direction growth on inclined m-plane facets of the nitridated islands. The determined lattice constants show nanorods which are strain free. The growth direction of the nanorods has been confirmed in a transmission electron microscope by convergent beam electron diffraction patterns to be in the N-polar [Formula: see text] direction.
Institute of Solid State Physics-Semiconductor Epitaxy-University of Bremen, Bremen, Germany. figge@ifp.uni-bremen.de
S
S
Figge
T
T
Aschenbrenner
C
C
Kruse
G
G
Kunert
M
M
Schowalter
A
A
Rosenauer
D
D
Hommel