The Gas Sensing And Field Emission Properties Of ZnO Based Micro-nano Structures

ZnO micro-nano structure has an important influence on its gas sensing and field emission properties.In this paper,the ZnO/In₂O₃ belt-tooth was synthesized on the silicon substrate by chemical vapor deposition and the gas sensor was also fabricated.It was found that the sensor has very good gas sensitivity for acetylene.ZnO microrods array were also synthesized on the silicon by chemical vapor deposition and found to have good field emission properties.The main contents of this paper are as follows:At first,ZnO/In₂O₃ belt-tooth shape nano-heterostructures gas sensors have been fabricated on silicon substrate by using chemical vapor deposition.The ZnO/In₂O₃ belt-tooth shape nano-heterostructures gas sensor fabricated in this way showed good gas-sensing properties for acetylene at low operating temperature?90^oC?.Compared with the ZnO/In₂O₃belt-tooth shape nano-heterostructures gas sensors,the Au decorated ZnO/In₂O₃ belt-tooth shape nano-heterostructures gas sensors exhibit better gas sensing properties for acetylene such as higher response?5 at 90^oC to 100 ppm acetylene,while the other is 1.75 at the same condition?,less response time?8.5s at 90^oC to 100 ppm acetylene,while the other is 38s at the same condition?,better selectivity?response to C₂H₂?C₂H₅OH?CO?CH₄ and C₃H₈?and smaller deviation from the ideal value of power exponent??the ideal value is 0.5,the Au decorated is 0.5123,while the other is 0.4555?.The gas sensitivities of ZnO/In₂O₃ belt-tooth shape nano-heterostructures doped with Au are greatly increased because of the new depletion layer at the interface between Au nanoparticles and ZnO/In₂O₃ belt-tooth shape nano-heterostructures.At the operating temperature of 90^oC,both sensors showed good gas sensitive properties.What's more,at the working temperature of 30 days of continuous operation of the sensor still retains a good gas sensitive properties.Using zinc oxide and activated carbon mixed powders as raw materials,a mass ratio of1.5:1 was mixed together.ZnO microrods array with nanospikes was first fabricated on the silicon substrate by CVD method.It has been found that it has very good field emission property,such as a low turn-on electric field?3.1 V/?m when the current density is 10?A/cm²?and a higher current density under the same applied electric field.The growth mechanism of this sample can be explained by the gas-solid?VS?growth mechanism and secondary nucleation.