The Field Emission Properties Of Te Doped GaN Nanowires

Gallium nitride(GaN)is a kind of excellent wide bandgap semiconductor materials.GaN has excellent photoelectric properties,so it has attracted a lot of attention from the science and technology workers.As is known to all,the electron affinity of GaN is as low as 2.7-3.3 eV.In addition,GaN also possesses high melting point,high thermal conductivity and high carrier mobility,so it is suitable for application in vacuum microelectronic devices as a field emission cathode material.Some researchers have taken many methods to improve the field emission properties of GaN nanomaterials,such as changing the morphology of GaN nanomaterials,and doping or coating GaN nanomaterials.In this work,we will investigate the optimization of field emission properties of the Te-doped GaN nanowires,including theoretical calculation and experiment.Theoretically,the electronic structures and field emission properties of Te-doped GaN nano wires have been investigated by a first principle density functional theory(DFT).The results show that Ga atoms on the outmost-surface of GaN nanowires are more likely to be replaced by Te atoms,and the local electron states near the Fermi level are mainly introduced by Te atoms.The work function(WF),ionization potential(IP)and electron affinity(EA)of the Te-doped GaN nano wires decrease with the increase of the number of Te atoms.It suggests that the presence of Te atoms allows for a significant enhancement of the field emission properties.Experimently,we first investigate the synthesis of Te-doped GaN nanowires using chemical vapor deposition(CVD)method,and discuss the influencing factors on preparation of Te-doped GaN nanowires,like the quality ratio of Ga2O3 and Te,and the reaction temperature.X-ray diffraction(XRD),scanning electron microscopy(SEM)and Raman spectrum were used for characterizing the samples which synthesized by different growth conditions.Then,we test the field emission properties of Te-doped GaN nanowires with different doping concentration using the field emission devices,and conclude that the field emission properties of Te-doped GaN nanowires is better than the pure GaN nanowires.Combined with the result of theoretical calculation,we analyzed that the improvement of the field emission properties is due to the decrease of work function(WF)of the Te-doped GaN nanowires.