New Jersey Institute of Technology Digital Commons @ NJIT Theses Electronic Theses and Dissertations Spring 5-31-2015 Optical properties of black silicon - an analysis Suramya Sekhri New Jersey Institute of Technology Follow this and additional works at: https://digitalcommons.njit.edu/theses Part of the Materials Science and Engineering Commons Recommended Citation Sekhri, Suramya, "Optical properties of black silicon - an analysis" (2015). Theses. 244. https://digitalcommons.njit.edu/theses/244 This Thesis is brought to you for free and open access by the Electronic Theses and Dissertations at Digital Commons @ NJIT. It has been accepted for inclusion in Theses by an authorized administrator of Digital Commons @ NJIT. For more information, please contact [email protected]. Copyright Warning & Restrictions The copyright law of the United States (Title 17, United States Code) governs the making of photocopies or other reproductions of copyrighted material. 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ABSTRACT O PTICAL PR O PER TIES O FBLACKSILICO N -AN AN ALYSIS by S uramyaSekhri S ilicon isthe preeminent solarcellm aterialof the day becauseitisthe first semiconductorthatw aslearned to comm ercialize and continuesto be the principal semiconductingm aterialusedinphotovoltaictechnology forthem anufactureofsolar cells.S ilicon,anindirectbandgapsemiconductingm aterial,hasareflectanceofabout 30% inthe visiblerange ofw avelengths.S tandardS ilicon solarcellsarenot entirely usefulintheinfraredspectrum region.InordertoenhancetheperformanceofS ilicon solarcells,reflectancelossesmustbem inimizedandabsorptionm ustbem aximized.In thesolarcellindustry,anti-reflection(AR )coatingisusedtosuppressreflectionlosses. AR coatingsarelimited inusebecausethey onlyreducethereflectanceforanarrow rangeofw avelengthsandincidentanglesincetheirfunctionalityisbasedonaquarter- w avelength coating. S urface texturing isa technique,by w hich the reflectivity is reduced.BlackS ilicon isam aterialw ithsurfaceroughnessinthem icron scale. Black S ilicon,when used insteadofCrystalline S ilicon,offersthe possibility to increasethe absorptionoflightinthevisibleandinfraredrangeofw avelengths.BlackS iliconhasa verylow reflectivityinthevisiblerangeofw avelengths.Itexhibitshighabsorptancein thevisibleandinfraredregion. T hem ainobjectiveofthisthesisistostudy thevarious fabrication techniquesused to form Black S ilicon,present a comparative study of structuraldifferencesand analyze itsopticalpropertiesby simulation and compare them w ith the simulated and experimentalopticalpropertiesofBlack S ilicon and CrystallineS ilicon. O PTICAL PR O PER TIES O FBLACKSILICO N -AN AN ALYSIS by S uramyaSekhri A T hesis S ubmittedtotheFacultyof N ew JerseyInstituteofT echnology inP artialFulfillmentoftheR equirementsfortheDegreeof M asterofS cienceinM aterialsScienceandEngineering InterdisciplinaryP rograminM aterialsScienceandEngineering M ay2015 APPRO VAL PAGE O PTICAL PR O PER TIES O FBLACKSILICO N -AN AN ALYSIS S uramyaSekhri Dr.N .M .R avindra,ThesisAdvisor Date P rofessor,DepartmentofP hysics,N JIT Director,InterdisciplinaryP rograminM aterialsScience& Engineering,N JIT Dr.M ichaelJaffe,Comm itteeM ember Date R esearchP rofessor,DepartmentofBiomedicalEngineering,N JIT Dr.HalinaO pyrchal,Comm itteeM ember Date S eniorU niversityL ecturer,DepartmentofP hysics,N JIT M r.B.S .M ani,Comm itteeM ember Date U niversityL ecturer,DepartmentofM echanical& IndustrialEngineering,N JIT Dr.W illisB.Hamm ond,Comm itteeM ember Date CEO ,W .B.Hamm ondAssociates,LL C BIOGR AP HICAL SKETCH Author: S uramyaSekhri Degree: M asterofS cience Date: M ay2015 U ndergraduateandGraduateEducation: M asterofS cienceinM aterialsScienceandEngineering, N ew JerseyInstituteofT echnology,N ewark,N J,U S A,2015 BachelorofS cienceinP hysics, KiroriM alCollege,U niversityofDelhi,Delhi,India,2013 M ajor: M aterialsScienceandEngineering iv T othefivepillarsofmy life:God,my Grandparents,andm y P arents. W ithoutyou,my lifew ouldfallapart. Imightnotknow w herethelife’sroadw illtakem e, butw alkingw ithYou,God,throughthisjourneyhasgivenmestrength. M om,you havegivenmesomuch,thanksforyourfaithinm e, andforteachingm ethatIshouldneversurrender. Daddy,you alwaystoldm eto“ reachforthestars.” IthinkIgotm yfirstone. T hanksforinspiringmeforeverythinginlifeandofcourse,Physics! v ACKN O W L EDGEM EN T S Iw ouldliketoexpressmy deepestappreciationtom y thesisadvisorDr.N .M .R avindra w ho hasthe attitude and substance ofa genius.He continuallyand convincingly conveyed a spiritofadventureinregard to m y thesisand research. W ithout his guidanceandpersistenthelpthisthesiswouldnothavebeenpossible.T hanksforgiving m etheopportunitytobepartoftheBlackS iliconresearch. S pecialthankstoallmy thesiscomm itteemembersDr.M ichaelJaffe,Dr.Halina O pyrchal,M r.B.S .M ani,Dr.W illisB.Hamm ondfortheirvaluabletime andforserving onm y comm ittee. S pecialT hankstoM s.ClarisaGonzalez,AssociateDirectorofGraduateS tudies and M s.L illianQ uiles, AdministrativeAssistantat the GraduateS tudiesO fficefortheir valuableandeffectiveinputsandhelpingm eimprovem y overallthesis. Iam gratefultoallmy researchgroup m embers:S itaL axmi,ChiranjiviL amsal, VishalN akhate,AniketM aske,SarangM uleyw hohavesupportedmethroughoutentire process,bothbykeepingm eharmoniousandhelpingmeputtingpiecestogether. Iamhighlygratifiedbym y Grandparents:M r.M adanL alSekhriandM rs.S udesh S ekhriand parents:M r.Vikram S ekhriand M rs.Anu S ekhrifortheirlimitlessand imm ensesupport,encouragement and blessings.T hank you foralwaysboosting m y m oraleandkeepingfaithinm e.Iappreciatem y sibling:R ohinyaS ekhri’snever-ending beliefinm e and forbeing therethroughthickand thin.M y deepestgratitude tom y vi friendsbackinIndiaforalwayskeepingm y spiritshighandforalltheencouragement andpraise. vii TABLEO FCO N TEN TS Chapter P age 1 INTRO DU CTION ………………………………………………………………………………………………….. 1 2 SILICO N -AN AN ALYSIS……………………………………………………………………………………….. 4 2.1 N aturalAbundance………………………………………………………………………………………. 4 2.1.1 AmorphousSilicon………………………………………………………………………….…. 4 2.1.2 CrystallineS ilicon…… … … … … … … … … … … … … … … … … … … … … … … … … … … … … 6 2.2History………………………………………………………………………………………………………… 6 2.2.1 Firsttimepreparation-1823… … … … … …… … … … … … … … … … … … … … … … … … … 7 2.2.2 CrystallineS ilicon-1854… … … … … … … …… … … … … … … … … … … … … … … ..…… .… 7 2.2.3 T oday’sScenario…………………………………………………………………………………. 7 2.3 O ccurrence………………………………………………………………………………………………….. 8 2.4 P roperties…………………………………………………………………………………………………….. 9 2.4.1 P hysical……………………………………………………………………………………………….. 9 2.4.2 Chemical……………………………………………………………………………………………… 11 2.5Applications……………………………………………………………………………………….………….. 12 2.5.1 Solar…………………………………………………………………………………………….………. 12 2.5.2 Electronics……………………………………………………………………………………….…… 13 2.5.3 S emiconductors…………………………………………………………………………………. 14 2.5.4 Glasses……………………………………………………………………………………………….. 15 2.5.5Ceramics…………………………………………………………………………………………….. 15 2.5.6FiberO ptics……………………………………………………………………………….………. 16 2.5.7P olymers…………………………………………………………………………………………….. 16 viii TABLEO FCO N TEN TS (Continued) Chapter P age 3 BLACKSILICO N …………………………………………………………………………………………………… 19 3.1 BlackS iliconHistory…… … … … … … … … … … … … … … … … … … … … … … … … … … .…… … … … 19 3.2 P roductionP rocesses…………………………………………………………………………………… 20 3.3 M ethodsofFabricatingBlackS ilicon…… … …… … … … … … … … … … … … … … … … … … … . 20 3.3.1 DryEtching………………………………………………………………………………………….. 21 3.3.2 W etchemicaletching…… … … … … … … … … … … … … … … … … … … … … … … … … … … .. 26 3.3.3 T heLaserM ethod………………………………………………………………………………… 33 3.3 S urfaceAnalysis……………………………………………………………………………………………. 36 3.3.1 S cienceofsurfaceroughness…… … … … … … … … … … … … … … … … … … … .…… … … . 36 3.3.2 ComparativestudyofBlackS iliconS EM images-RIE…… … … … … … … … … … 38 3.3.3 ComparativestudyofBlackS iliconS EM images-PIII…… … … … … … … … … … 39 3.3.4 ComparativestudyofBlackS iliconS EM images-BoschR IE……… … … … … . 40 3.3.5ComparativestudyofBlackS iliconS EM images-M ACE…… … …… … … … … . 41 3.3.6ComparativestudyofBlackS iliconS EM images- Femtosecondlaser……………………………………………………………………………….. 43 3.3.7Comparisonofthesurfacesbyallfabricationm ethods…… … … … … … … … … 50 4 O PTICAL PRO PERTIES………………………………………………………………………………………….. 52 4.1 Comparisonofopticalproperties-allmethods…… … … … … … … … … … … … … … … … . 53 4.1.1 R IE-PIII…………………………………………………………………………………………………