The III-Nitride semiconductor systems of InN, GaN, AlN and their ternary alloys are of great technological importance due to their direct and wide bandgaps and their refractory properties. The alloy system spans a wide energy spectrum ranging from 0.7 eV for InN to 3.4 eV for GaN to 6.2 eV for AlN, and has a direct bandgap over the entire range. Thus, growth of high-quality films based on these materials can lead to optical devices functioning in the range of visible and ultraviolet (UV) energies, which were previously not accessible. In addition, the strong atomic bonding and thermal stability of these compounds have made them very attractive for device applications. However, it is not easy to obtain a high-quality GaN materials because of the large lattice mismatch and the difference in the thermal expansion coefficients between GaN and foreign substrates. Among the several methods for achieving a high-quality GaN products, the most desirable way is the formation of the single crystal with one-dimensional (1-D) nanostructures, such as nanowires and nanorods. In this thesis, structural properties of 1-D GaN nanorods grown by hydride vapor phase epitaxy without a catalyst were characterized.
Vertically aligned GaN nanorods were synthesized on Si (111) substrates by HVPE method without a catalyst at different growth temperature condition. General morphologies of GaN structure, such as diameter, length, surface morphology, etc., were seriously affected by the growth temperature. The surface morphology was observed to change significantly with growth temperature, especially affected by temperature in third zone. Side facet planes of the tip region of GaN nanorods consisted of ${\overline{1}100}$, ${\overline{1}102}$, and ${\overline{1}103}$. The side facet plane of GaN nanorods consistes of {$\overline{1}$100} and ${\overline{1}10N}$ (N is integer) and N is increased as the temperature in third zone is increased. In initial formation stage, nuclei of GaN materia...