Studies On Preparation And Roperties Of GaN Nanowires By PECVD

Gallium nitride(GaN),a third-generation semiconductor material,is a direct bandgap wide bandgap semiconductor with excellent properties,such as high electron saturation speed,carrier mobility,high thermal conductivity,and meanwhile owning excellent performance in breakdown strength and high temperature resistance,corrosion resistance and radiation resistance.GaN nanowires,as low-dimensional semiconductor nanostructures,have unique characteristics of size and performance advantages,and have potential applications in nanooptoelectronic devices and highpower nanoelectronic devices,including ultraviolet light-emitting diodes,field effect transistors,photodetectors,nanolasers and biochemical sensors since its unique dimensional and performance advantages.On the basis of previous studies,this paper proposes a simple,inexpensive and environmentally friendly method in preparing GaN nanowires,and further studies the regulation growth,photoelectric properties and electrocatalysis applications of the nanowires.The main research progresses are as follows:1.Using a low-cost plasma enhanced chemical vapor deposition system(PECVD)with isotropic graphite as the substrate and metal gallium as the gallium source without any catalyst.The GaN nanowires with a diameter ranging from 90 to 200 nm and a length ranging from 4 to 20 ?m were prepared by direct reaction Ga atoms and N plasma.The morphology,structure and composition of the prepared nanowires were characterized,which shows that the prepared products are hexagonal wurtzite GaN nanowires that have polycrystalline structures,and they have the three-dimensional pyramid island structure.Further,the effects of process parameters(growth temperature,RF power,growth time,gas flow)on the morphology and properties of the prepared nanowires were also investigated.In addition,through a series of experiments and characterization analysis,we proposed a model for nucleation and growth of GaN nanowires without catalysts.This method will provide a novel alternative to low-cost,large-scale production of GaN nanowires.2.The photoluminescence(PL)and field emission properties of the prepared GaN nanowires were systematically investigated.The research progresses are as follows: GaN nanowires have good PL properties,and the morphology of the nanowires has a significant effect on their PL properties.The prepared GaN nanowires have a low turnon voltage(4-6 V/?m)and an excellent field emission performanceand the structure morphology of nanowires has a certain influence on their field emission performance.Further,the influence mechanism of structure on field emission performance was studied.4.The electrocatalytic properties of GaN prepared nanowires were investigated.The results show that the polycrystalline GaN nanowires prepared by this method exhibit excellent electrocatalytic hydrogen evolution performance without modification and supporting,and the hydrogen evolution potential is 280 mV,which may be due to the rough and protruding surface morphology of the polycrystalline GaN nanowires,which can provide a large number of active sites in the catalytic process of electrolyzed water,which is beneficial to the diffusion of electrolyte and the generation and desorption of gases.The prepared polycrystalline GaN nanowires are expected to replace traditional noble metal electrocatalytic materials and realize low-cost and highperformance electrocatalytic devices.