TOF SIMS analysis, structure and photoluminescence properties of pulsed laser deposited CaS:Eu2+ thin films

CaS:Eu2þ thin films weredepositedonSi(100)substratesusingthepulsedlaserdepositiontechniqueto investigatetheeffectofargon(Ar),oxygen(O2), andvacuumdepositionatmospheresonthestructural, morphological andphotoluminescencepropertiesofthethin films. Thephosphortargetwasablated using a266nmNd:YAGlaser.X-raydiffraction,atomicforcemicroscopy,scanningelectronmicroscopy, energy dispersiveX-ray, fluorescencespectrophotometryandtime-of-flight secondaryionmassspec- trometry wereusedtocharacterizethethin films. Thethin films preparedinoxygenwereessentially amorphous, whilethosepreparedinargonandvacuumshowedsomedegreeofcrystallinity.The film deposited inArshowedbetterphotoluminescenceintensitythanthosedepositedinanO2 and vacuum. The emissionobservedataround650nmforallthe films isattributedtothetransitionsfromtheexcited 4f F 5dt 6 0 7 1 [ ] ( 2g) state tothegroundstate 4f7 S 7/2 8 ( ) of theEu2þ ions. Theemissionat618nm,whichismore prominent inthe film preparedinO2, isascribedtothe 5D F 0 2 7 → transitions inEu3þ, suggestingthatEu2þ wasunintentionallyoxidizedtoEu3þ. Theatomicforcemicroscopydatashowedthatthe film prepared in argonwasrougherthanthosepreparedinoxygenandvacuum. This workwas financially supportedbythecompetitivepro- gramme forratedresearchers(Grantno.CPR20110724000021870) of theSouthAfricanNationalResearchFoundation(NRF),the South AfricanResearchChairsInitiativeoftheDepartmentof Science andTechnology(Grantno.84415)therentalpoolpro- grammeoftheNationalLaserCentre(NLC)(Grantno.NLC- LREGM00-CON-001). CaS:Eu2þ thin films weredepositedonSi(100)substratesusingthepulsedlaserdepositiontechniqueto investigatetheeffectofargon(Ar),oxygen(O2), andvacuumdepositionatmospheresonthestructural, morphological andphotoluminescencepropertiesofthethin films. Thephosphortargetwasablated using a266nmNd:YAGlaser.X-raydiffraction,atomicforcemicroscopy,scanningelectronmicroscopy, energy dispersiveX-ray, fluorescencespectrophotometryandtime-of-flight secondaryionmassspec- trometry wereusedtocharacterizethethin films. Thethin films preparedinoxygenwereessentially amorphous, whilethosepreparedinargonandvacuumshowedsomedegreeofcrystallinity.The film deposited inArshowedbetterphotoluminescenceintensitythanthosedepositedinanO2 and vacuum. The emissionobservedataround650nmforallthe films isattributedtothetransitionsfromtheexcited 4f F 5dt 6 0 7 1 [ ] ( 2g) state tothegroundstate 4f7 S 7/2 8 ( ) of theEu2þ ions. Theemissionat618nm,whichismore prominent inthe film preparedinO2, isascribedtothe 5D F 0 2 7 → transitions inEu3þ, suggestingthatEu2þ wasunintentionallyoxidizedtoEu3þ. Theatomicforcemicroscopydatashowedthatthe film prepared in argonwasrougherthanthosepreparedinoxygenandvacuum.