Synthesis And Field Emission Properties Of Three-Dimensional Branched GaN Nanowire Homostructures

Gallium nitride(GaN)is a kind of typical ?-? semiconductor material with a direct wide band gap(3.4 eV)?low electron affinity(2.7-3.3 eV).high melting point(1700?)?low work function(4.1 eV)and other excellent properties,so that it is an excellent field emission cathode material and it can be used as the field emission devices.The physical and chemical properties of GaN nanomaterials are better than those of GaN bulk materials.In order to further improve the field emission properties of GaN materials,we prepared three-dimensional br anched GaN nanowire under different conditions and studied the growth mechanism,crystal structure and field emission properties of the samples.We have synthesized three-dimensional branched GaN nanowire homostructures in horizontal tube furnacewere via chemical vapor deposition(CVD)and the two step approach,and the samples were characterized.First of all,we studied the effect of temperature and ammoniating time on three-dimensional branched GaN nanowire homostructures.It was found that GaN nanowires with uniform branches were prepared,when the temperature was 1030? and ammoniating time was 15 min.Secondly,we studied the the crystal structures and field emission properties of three-dimensional branched GaN nanowire homostructures with good morphology.The result of X-ray diffraction showed that the sample was hexagonal wurtzite structure.The result of TEM showed that the trunks grown in the(0001)direction,and six branches epitaxially grown on six sides of trunks.The result of EDS showed that three-dimensional branched GaN nano wires have high the purity.Field emission test showed that three-dimensional branched GaN nanowires have the low field(2.35V/?m(0.01 mA/cm2))?high the field enhancement factor(2938).Field emission properties of the three-dimensional branched GaN nanowires were better than those of the other nanostructures.Accordingly,three-dimensional branched GaN nanowires should be a promising nanomaterial in all kinds of nanoelectronic device applications.