NANOSCALE POROUS SILICON PHOTONIC MICROCAVITY STRUCTURES FOR OPTICAL SENSING OF ETHANOL

摘要

Poroussilicon(PS)isemergedasauniqueandpromisingnanomaterialfortheoptoelectronicdevicesandthesensingapplications.Inthisstudy,nanoscalePSphotonicmicrocavity(MC)sensordevicestructures,preparedbyanodizationofcrystallinesiliconwafer,areproposedasalargesurfaceareamatrixforsensingthedifferentconcentrationsofethanolsolution.Fabry–PerotreflectancefringeswereobservedfromthePSMCstructurespreparedundertheanodizationconditionswithdifferentcurrentdensitiesandetchingtimeprofiles.TheopticalcharacterizationofthePSMCstructures,beforethermaloxidation,showedasharpphotonicresonanceandblueshiftedandnarrowedafterthermaloxidationprocess.ThephotonicresonancewavelengthofPSMCsensordeviceshowedsignificantredshiftaftercapillaryadsorptionofethanolbecausethestructurerefractiveindexchangesafterinfiltrationoftheporesofthePSMCsensordevicestructures.TheresonancewavelengthshiftshowedalinearrelationshipwiththedifferentconcentrationsofethanolforthenaturaloxidizedPSMCstructuresandthermaloxidizedPSMCstructures.Thethermaloxidizedstructuresshowedbettersensibilityfeatureandthisresultwasattributedtopassivationofthesurfacedevices.Also,weobservetheabilityofreversiblesensingbyPSMCsensordevicestructures.