Low, Li Li
(2012)
Fabrication Of Gallium Nitride Nanowires Via Chemical Vapour Deposition.
Masters thesis, Universiti Sains Malaysia.
Abstract
In this project, works are focusing on the investigation of the growth and
characterization of GaN nanowires synthesized by Ni-catalyzed chemical vapour
deposition under various experimental parameters including gallium source and
substrate position, growth temperature, ammonia flow rate and reaction period. The
comparative studies of the influence of these parameters on the morphological,
structural and optical characteristics of the synthesized GaN were carried out in this
project. The morphology of the synthesized GaN low dimensional wires was dependent
on the position of Ga precursor and substrates. The position of Ga precursor and
substrates was found to be able to affect the degree of supersaturation of gaseous
reactants, which is essential in the growth of GaN wires by vapour-liquid-solid
mechanism. Thus two different dimensional aspects of GaN micro- and nanowires
were synthesized in this parameter study. The study of growth temperature revealed
that 950ºC was the optimal growth temperature for synthesizing uniform, straight and
smooth morphology of GaN nanowires with good elemental composition. On the other
hand, the morphology and growth mechanism of GaN nanowires were dependent on
NH3 flow rate. It was found that straight GaN nanowires were synthesized under low
NH3 gas flow rate via vapour-liquid-solid mechanism whereas vermicular-like
nanowires were synthesized under high NH3 gas flow rate via the vapour-solid
mechanism. Additionally, the study of reaction period revealed that the synthesized
GaN nanowires showing a uniform and straight morphology in the early growth
process and subsequently transforming to vermicular-shape of nanowires with the
increase of reaction period.
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