The Preparation And First-principle Study Of Sb-doped GaN Nanowires

GaN is a wide direct band gap(3.4 eV)III nitride semiconducting material,which is widely used in optoelectronic and microelectronic devices because of its excellent optical properties,electrical properties and good chemical,physical stability.In addition,GaN material has a high thermal conductivity,small electron affinity(2.7-3.3 eV)and work function,so that it is a promising field emission cathode material,which has became a hot research in the world.The theoretical calculation and experimental preparation of Sb-doped GaN nanowires were mainly studied in this work.In theory,the formation energies,electronic structures(including energy bands,density of states,local charge density)and work functions of Sb-doped GaN nanowires with different concentrations have been investigated by density functional theory based on the first-principle.The results show that Sb atom is more likely to substitute Ga atom on outermost surface of GaN nanowires to form the most stable structure.The impurity levels near the bottom of conduction band and the top of valence band are introduced by Sb dopant,so that the band gaps of GaN nanowires are decreased.The electronic states near the bottom of conduction band are maily contributed by Sb atoms.The local charge near the bottom of conduction band is mainly produced by the interactions between Sb atoms and several N atoms near the Sb atoms.The work functions of the single and pair Sb-doped GaN nanowires are slightly less than the undoped GaN nanowires.it predicted that Sb dopant can improve the field emission properties of GaN nanowires in theoretically.In the experiment,Sb-doped GaN nanowires grown on Pt-catalyzed Si(111)substrate were synthesized via chemical vapor deposition method,and Ga2O3 as Ga source,NH3 as N source and Sb as the doped source.We studied the effect of the ammoniation temperature,ammoniation time,ammonia flow and doping mass ratio on the morphology of Sb-doped GaN nanowires.Sb-doped GaN nanowires of different doping mass ratios were characterized by XRD,EDS.The results show that the good morphology of Sb-doped GaN nanowires was synthesized at 1040 ℃,30 min,250 seem conditions.Synthesis of Sb-doped GaN nanowires follows the VLS mechanism.The synthesized Sb-doped GaN nano wires are hexagonal wurtzite structure,and Sb atoms dope into the GaN nano wires.With the increase of doping mass ratios,the crystallinity of GaN nanowires is become weak.