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1、PHYSICALREVIEWB71,153402s2005dElectronicexcitationspectrumofmetalliccarbonnanotubesS.Sapmaz,P.Jarillo-Herrero,J.Kong,C.Dekker,L.P.Kouwenhoven,andH.S.J.vanderZantKavliInstituteofNanoscience,DelftUniversityofTechnology,P.O.Box5046,2600GADelft,TheNetherlandssReceived17December2004;published8April2005
2、;corrected15April2005dWehavestudiedthediscreteelectronicspectrumofclosedmetallicnanotubequantumdots.Atlowtem-peratures,thestabilitydiagramsshowaveryregularfourfoldpatternthatallowsforthedeterminationoftheelectronadditionandexcitationenergies.Themeasurednanotubespectraareinexcellentagreementwiththe
3、theoreticalpredictionsbasedonthenanotubebandstructure.Ourresultspermitthecompleteidenti®cationoftheelectronquantumstatesinnanotubequantumdots.DOI:10.1103/PhysRevB.71.153402PACSnumberssd:73.22.Dj,73.63.Fg,73.23.HkSincetheirdiscovery1carbonnanotubessNTsdhaveCVDnanotubesaregrownfromcatalystparticleso
4、npre-emergedasprototypicalone-dimensionalconductors.2Atde®nedpositions.IndividualNTsarelocatedbyatomicforcelowtemperatures,NTdevicesformquantumdotssQDsdmicroscopysAFMdwithrespecttoprede®nedmarkerposi-wheresingle-electronchargingandlevelquantizationeffectstions.Electrodesaredesignedontopofstraights
5、egmentsofdominate.3,4AcontinuousimprovementindevicefabricationNTs.ThehighlydopedsiliconisusedasabackgatetoandNTqualityhasenabledtherecentobservationoftwo-changetheelectrostaticpotentialoftheNTQDfseeFig.electronperiodicityinªclosedºQDs5andfour-electronperi-1sbdg.WefabricateNTdeviceswithlengthsinbet
6、weencon-odicityinªopenºsingle-wallandmultiwallNTQDs.6,7tacts,L,varyingfrom100nmto1mm.Afour-electronshellTheoretically,thelow-energyspectrumofsingle-wallnano-®llingisobservedinover15samples.InsomecasesthetubesSWNTdQDshasbeenmodeledbyOregetal.8Experi-fourfoldpatternextendedovermorethan60electronsadd
7、edmentsonopenNTQDsarecompatiblewiththismodel,buttotheQD.Figures1sdd±1sfdshowrepresentativeexamplesthepresenceoftheKondoeffectandbroadeningoftheen-149ofCoulombblockadesCBdoscillationsinthelinear-ergylevelsprevents