Transientphotoconductivityanditslight inducedchangewereinvestigatedbyusingaModel440 0boxcaraveragerandsignalprocessorforlightlyboron dopeda Si∶Hfilms.Thetransientphotoconductivitiesofthesampleweremeasuredatanannealedstateandlight soakedstates.Thetransientdecayprocessofthephotoconductivitycanbefittedfairlywellbyasecond orderexponentialdecayfunction ,whichindicatesthatthedecayprocessisrelatedwithtwodifferenttraps.Itisnoteworthythatthephotoconductivityofthefilmincreasesafterlight soaking.ThismaybeduetothedeactivityoftheboronacceptorB-4,andthussomeoftheboronatomscannolongeractasacceptorsanddrivesEFtoshiftsupward .Consequently,thenumberofeffectiverecombinationcentersmaybereducedandsothephotoconductivityincreases.