Comparative Study of Low Pressure Sensing Performance for Carbon Nanotube and Zinc Oxide Nanorod Field Emitters
A field emission low pressure gas sensing technique based on gas adsorption effects was developed.In this work,CNTs were grown directly on Ni alloy substrates by thermal chemical vapor deposition(CVD)method,ZnO nanorodes were prepared by the hydrothermal method,and the Al-N co-doped ZnO nanorodes were further synthesized by CVD.Then the field emission and low pressure N2 sensing performances were investigated for CNT and ZnO nanorode field emitters.The results show that CNT emitters present good field emission performance with the turn-on field of 1.99 V/μm,while ZnO emitters show higher turn-on field of 14.9 V/μm.With the doping of Al-N elements,the field emission performance is improved significantly with the turn-on field of 8.9 V/μm.In the pressure range of 10-4-10-7 Pa,the CNT cathodes demonstrate best sensing behavior,and the sensing current rises up to 350％within 5 min test under N2 pressure of 10-4 Pa.The pristine ZnO emitters show almost no sensing effect,but Al-N co-doped ZnO emitters display decent sensing behavior,indicating that Al-N doping effectively improves the gas sensing performance resulting from the addition of active sites on the ZnO emitter.
field emissioncarbon nanotubezinc oxidelow pressureN2 sensing
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