Fabrication And Properties Of SiC Nanocone Field Emission Arrays

Silicon carbide（SiC）,as the third-generation wide-bandgap semiconductor,has excellent properties such as high breakdown field strength,high thermal conductivity,high physicochemical stability,low electron affinity and high electron mobility,which makes SiC has great room for exploration in field electron emission cold cathodes.Due to the extremely high aspect ratio,one-dimensional SiC nanomaterials provide a high field enhancement effect for field electron emission,so the low-dimensionalization of SiC materials has become an important research direction for SiC field emission.Common one-dimensional SiC nanostructured field emitters mainly use gas-phase synthesis,that is,pyrolysis of carbon source and silicon source under high temperature and high pressure and precipitation and precipitation of SiC nanowires,nanoribbons,nanosheets,nanorods,etc.These emitters show good emission performance and application potential.However,the emitters prepared by this"bottom-up"method often have problems such as different orientations,low purity,high growth temperature,and inconvenience to cooperate with other integrated circuits.In order to solve these problems,this thesis explores the"top-down"fabrication of vertically oriented SiC nanospike arrays as field emission cathodes on 4H-SiC single crystal substrates using mature dry etching techniques..The specific research contents are as follows:（1）Preparation of SiC taper array by dry etching under metal mask and its field emission properties.In order to obtain SiC nanocone arrays with tunable density and arrangement,the preparation process firstly uses electron beam exposure system to inscribe the designed circular array pattern on the 4H-SiC carbon enrichment surface spin-coated with PMMA（950k）electron beam glue（C-Face）,then the electron beam evaporation process was used to deposit metal Ni on the surface of the substrate as an etching mask,and finally the obtained substrate containing the metal mask pattern was etched using inductively coupled plasma to obtain SiC sharp cones array.The shape of SiC nano-taper is mainly controlled by dry etching parameters.The shape of SiC nano-taper under different etching times was explored.The expected tip radius of 10 nm～20nm and height of 2.05μm were obtained under the etching time of 5 min 30 s.μm SiC nanospike array.The field emission test results show that the SiC nano-spike array obtained by etching for 5 min30s（the distance between the cones is 5μm and the array area is 4mm²）has an open electric field of 4.42 V/μm and a field enhancement factor of 801,showing good field emission performance.（2）Fabrication of SiC taper arrays by maskless dry etching and their field emission properties.In this paper,through the optimization of reactive ion etching parameters,under the conditions of no lithography,no mask,and no oxidation corrosion,using reactive ion etching,and using SF₆/O₂ to anisotropically etch the 4H-SiC carbon surface.Large-area,high-density SiC nanocone arrays.In the characterization test part,the generation of this SiC nanocone array is expounded,and the morphological characteristics,the elemental composition analysis and field emission performance of the SiC nanocone array under the etching time of 10 min,20 min,30 min,60 min are explored respectively.Among them,the sample under the etching time of 20min showed the highest aspect ratio of 35,the field enhancement factor reached 1260,the turn-on electric field was as low as 4.37 V/μm,and the 8-hour emission current stability test showed extremely low volatility—about is 1.9%,showing excellent field emission performance.