The AlN nanostructures with a wide band-gap of 6.28 eV are considered as ideal cold cathode materials because of their low electron-affinity. Many methods have been devoted to fabricating AlN nanostructures, but high growth temperature over 800°C and the use of the catalysts in most methods limit their practical application and result in their poor field-emission behaviours in uniformity. This paper reports that without any catalysts, a simple chemical vapour deposition method is used to synthesize aligned AlN nanocone arrays at 550°C on silicon substrate or indium tin oxide glass. Field emission measurements show that these nanocones prepared at low temperature have an average turn-on field of 6 V/μm and a threshold field of 11.7 V/μm as well as stable emission behaviours at high field, which suggests that they have promising applications in field emission area.
The controllable growth of three different morphologies of AlN nanostructures(nanorod,nanotip and nanocrater) arrays are successfully realized by using chemical vapour deposition(CVD) technology.All three nanostructures are of single crystal h-AlN with a growth orientation of[001].Their growth is attributed to the vapour-liquid-solid(VLS) mechanism.To investigate the factors affecting field emission(FE) properties of AlN nanostructures,we compare their FE behaviours in several aspects.Experimental results show that AlN nanocrater arrays possess the best FE properties, such as a threshold field of 7.2 V/μm and an emission current fluctuation lower than 4%.Moreover,the three AlN nanostructures all have good field emission properties compared with a number of other excellent cathode nanomaterials, which suggests that they are future promising FE nanomaterials.
