Abstract: Thecathodematerialsusedinelectronmultiplier，fieldemission cathodeandparticle/photondetectorhavetheproblemoflowsecondaryelectronemissionyieldand unstableemission.Tosolvethisproblem， differentboronconcentrationdiamondfilmsbymicrowaveplasmachemicalvapordepositionwereprepared .ThesurfaceofB-dopeddiamondfilmwastreatedbyHydrogenplasma.Thesecondaryelectronemissi on（SEE）fromB-dopeddiamondfilmswasinvestigated. Thescanningelectronmicroscopy（SEM）andtheRamanspectrumanalysiswereusedtoexaminethepropertiesoftheB-dopeddiamondfilm. ThemaximumSEEyieldupto18.3at1keVprimarybeamenergywasfoundundertheconditionthatthesampleswereleftinairforweeksandsubjecttonotreatmentpriortothemeasurement.Oxidationtreatmentdestroysnegativeelectronaffinity（NEA）whereasheatingupinvacuumsubstantiallybringsbackNEA.B-dopeddiamondfilmisexpectedtobeusedinelectronmultiplier，fieldemissioncathodeandparticle/photondetector.

Key words: B-dopeddiamondfilms, microwaveplasmachemicalvapordeposition, secondaryelectronemission（SEE）yield, negativeelectronaffinity（NEA）, electronmultiplier