Study On Preparation And Properties Of AlN Nanowire Arrays

Aluminium nitride(AIN)has a 6.2eV band gap and belongs to direct band gap semiconductor,so it has great potential in photoelectronic devices at the high frequency of green,blue and ultra-violet.One-dimensional nano materials show potential applying in the optoelectronic,electrochemical and electromechanical field because of their unique electrical,thermal and mechanical properties.In recent years,it has been attracted much attention in the applying of field emission,light emitting diode(LED),laser diode,UV photodetector and preparation methods of AlN nanowires and its array.Compared with one-dimensional AlN nanostructures,AlN nanowires array has great application potential in the composite material and nano devices because of the specific performance.Although there are several methods to prepare the AlN nanowires array,the challenges of controllable preparation,macrosynthesis,good performance,simple preparation methods and low price AlN nanowires array remains.So it is research hotspot to find a way of preparation for high-quality AIN nanowires array.The AlN nanowires macro array with uniform orientation and diameter was prepared by double template method.A uniformly distributed PS spherical template was formed on the single crystal Si(001)surface by self-assembly characteristics of PS ball.A layer of metal Al nanoparticles were evaporated on the above templates by vacuum coating.After heat treatment,the Al nanoparticle template was formed.AlN nanowires array was synthesized by chemical vapor deposition on the Al nanoparticle template as cataly.Its area is about 0.3×0.2mm~2.The result of HRTEM and SEM shows that Al N nanowires is bent,and is uniformly of the diameter and length.The average diameter of nanowires is about 41nm and the average length of the nanowires is about 1.8?m.AlN nanowires number density is about 5.4×10~7/mm~2 and coverage rate is about 7.1%.The result of SAED and XRD shows that AlN nanowires is well crystallized and the structure is wurtzite.UV absorbance and reflectivity of Al N nanowires array were tested by the UVSP.The result shows that Al N nanowires array has preferable luminescence property in 150310nm,and the band gap is 6.08eV and less than AlN theoretical band gap of 6.2eV.Al N nanowires array belongs to direct band gap semiconductor.The band,density and optical properties of Al N nanowires with diameters of 1.24nm,1.56nm and 1.87nm were calculated by first principles and compared with the experiment results.The calculated band gap of 1.24nm is 5.24eV and less than the experimental date,because the band gap of first principles calculation is generally low.With the increase of diameter,the two peak positions of ultraviolet absorption are red shifted and the peak value of absorption spectrum is also increased 200~800nm.UV absorbance of AlN nanowires in200~800nm are good agreement with experimen results.The excellent optical performance of AlN nanowire has been proved.And the Al N nanowires array is the preferred material for UV and UV detectors.