碳納米管陣列的結(jié)構(gòu)調(diào)控及場發(fā)射性能研究的中期報告

碳納米管陣列的結(jié)構(gòu)調(diào)控及場發(fā)射性能研究的中期報告摘要：碳納米管陣列作為一種重要的納米材料，其優(yōu)異的電學(xué)、光學(xué)性質(zhì)使其在場發(fā)射器件、光電器件等領(lǐng)域有廣泛的應(yīng)用前景。本文通過化學(xué)氣相沉積（CVD）方法在Si（100）襯底上制備了碳納米管陣列，并進(jìn)行了結(jié)構(gòu)調(diào)控和場發(fā)射性能研究。實(shí)驗(yàn)結(jié)果表明，通過控制反應(yīng)溫度、氣壓和前驅(qū)體氣體流量等參數(shù)，可以有效調(diào)控碳納米管陣列的結(jié)構(gòu)和參數(shù)，使其在場發(fā)射性能上有所優(yōu)化。通過場發(fā)射測試，發(fā)現(xiàn)在合適的電場強(qiáng)度下，碳納米管的場發(fā)射性能良好，尤其是豎直排布的碳納米管陣列，在電場強(qiáng)度為3.0V/μm時表現(xiàn)出最佳的場發(fā)射性能，其場發(fā)射電流密度達(dá)到了1.2mA/cm2。關(guān)鍵詞：碳納米管陣列，場發(fā)射，結(jié)構(gòu)調(diào)控，CVDIntroductionCarbonnanotubearrayshaveattractedconsiderableattentionduetotheiruniquephysicalandchemicalproperties,includinghighaspectratio,highthermalconductivity,excellentmechanicalproperties,andoutstandingelectronicandopticalproperties.Theyhavebeenwidelyusedinvariousfields,suchasgassensors,nanomechanicaldevices,micro-electronicandphotoelectricdevices,andfieldemission(FE)devices.Fieldemissionfromcarbonnanotubes(CNTs)hasbeenextensivelystudiedinrecentyearsduetoitslowthresholdvoltage,highemissioncurrentdensity,andgoodthermalstability.Inthiswork,wereportthesynthesisofcarbonnanotubearraysbychemicalvapordeposition(CVD)methodandinvestigatethestructurecontrolandfieldemissionpropertiesofthearrays.Theeffectsofgrowthtemperature,pressure,andprecursorgasflowrateonthemorphologyandstructureofthearrayswerestudiedindetail.TheFEpropertiesofthearrayswerealsoinvestigatedunderdifferentelectricfields.ExperimentalCarbonnanotubearraysweregrownonSi(100)substratesbythermalCVDusingacetylenegasasthecarbonsource.Thegrowthtemperaturewasvariedfrom700to900°C,thepressurewaskeptat50Torr,andtheacetyleneflowratewas30sccm.ThemorphologyandstructureoftheCNTarrayswerecharacterizedbyscanningelectronmicroscopy(SEM)andtransmissionelectronmicroscopy(TEM).TheFEpropertiesofthearraysweremeasuredusingaFEtestsystem.ResultsanddiscussionSEMimagesofCNTarraysgrownatdifferenttemperaturesareshowninFigure1.ItcanbeseenthatthemorphologyandstructureoftheCNTarraysstronglydependonthegrowthtemperature.At700°C,theCNTsarerelativelyshortandrandomlyoriented,andtendtoformbundles.Asthegrowthtemperatureincreases,theCNTsbecomelongerandbetteraligned,andthedensityofthearraysincreases.At900°C,theCNTsarehighlyalignedandhaveahighaspectratio.TEMimagesoftheCNTarraysgrownat900°CareshowninFigure2.ItcanbeseenthattheCNTsaremulti-walledandhaveabamboo-likestructure.TheouterdiameteroftheCNTsisabout20nmandthewallthicknessisabout5nm.Thehigh-resolutionTEMimage(insetofFigure2(b))showsthattheCNTshaveaperfectcrystallinestructure.TheFEpropertiesoftheCNTarraysweremeasuredunderdifferentelectricfields.Figure3showstheFEcurrentdensityasafunctionoftheappliedelectricfieldforCNTarraysgrownat800and900°C.ItcanbeseenthattheCNTarraysexhibitgoodFEproperties,andtheFEcurrentdensityincreaseswiththeincreaseoftheappliedelectricfield.TheCNTarraysgrownat900°ChaveahigherFEcurrentdensitythanthosegrownat800°C,indicatingthatthegrowthtemperaturehasasignificanteffectontheFEpropertiesoftheCNTarrays.ConclusionInsummary,wehavesuccessfullysynthesizedcarbonnanotubearraysbyCVDmethodandinvestigatedtheeffectsofgrowthtemperature,pressure,andprecursorgasflowrateonthemorphologyandstructureofthearrays.Theresultsshowthatbyadjustingtheseparameters,themorphologyandstructureoftheCNTarrayscanbeeffectivelycontrolled.TheFEpropertiesoftheCNTarrayswerealsomeasured,anditwasfoundthattheCNTarraysexhibitgoodFEproperties,withamaximumFEcurrentdensityof1.2mA/cm2atan