asihncsihasich多层薄膜的制备与光电特性研究word格式论文.docxVIP

摘要本课题采用射频等离子体增强化学气相沉积（RF-PECVD）技术，以SiH4、CH4和H2为反应气体，在单晶硅和石英衬底上制备a-Si:H/a-SiC:H多层薄膜，并采用高温热退火工艺获得nc-Si:H/a-SiC:H多层结构。利用透射电子显微镜(TEM)、X射线衍射(XRD)、Raman散射光谱、傅里叶红外吸收谱(FT-IR)等测试手段，对a-Si:H(nc-Si:H)/a-SiC:H多层薄膜样品的微结构进行了表征，同时对其光学和电学特性进行了实验研究。结果表明，本实验条件下制备的多层薄膜样品具有良好的周期性结构和陡峭的界面特性。样品经过高温退火后，在a-Si:H势阱层中形成了尺寸可控的Si纳米晶粒。室温条件下，发现未退火的多层样品在垂直方向上呈现出多势垒顺序共振隧穿特性，退火样品在高电场强度下的载流子输运符合Fowler–Nordheim(FN)隧穿机制。由于量子尺寸限制效应，随着势阱层厚度的减小a-Si:H(nc-Si:H)/a-SiC:H样品的光学带隙增大，光吸收系数减小，但势垒层厚度并没有对退火后nc-Si:H/a-SiC:H多层薄膜的光吸收系数和光学带隙产生较大影响。此外，多层膜样品在经过450℃退火后由于键合H原子的逸出导致样品中缺陷态密度增大，光学带隙减小。而900℃热退火使势阱层中形成Si 纳米晶粒，增强了其量子限制效应，导致样品的光学带隙展宽。关键词：PECVD多层薄膜微结构特征光学特性电学特性AbstractThea-Si:H/a-SiC:Hmultilayerfilmwaspreparedonthemonocrystallinesiliconandquartzsubstratesbyradiofrequencyplasmaenhancedchemicalvapordepositiontechnique(RF-PECVD),usingSiH4,CH4andH2asreactiongassources.Thenc-Si:H/a-SiC:Hmultilayerfilmswereannealedathightemperature.Themicrostructuresof a-Si:H(nc-Si:H)/a-SiC:Hsamplescharacterizedrepresentedusingtransmissionelectron microscope(TEM),X-raydiffractometer(XRD),Ramanspectroscopy,aswellasFouriertransforminfraredspectroscopy(FT-IR)testinginstruments. Atthesametime, theopticalandelectricalpropertiesofa-Si:H(nc-Si:H)/a-SiC:Hmutilayerfilmswereexperimentalstudied.Theresultsshowthatthemultilayerfilmsampleshavegoodperiodicstructureandsteepinterfaces.Size-controlledSinanocrystalsinwelllayerofa-Si:Hwerepreparedbyannealingathightemperature.Atroomtemperature,sequentialresonanttunnelingpeculiaritiesontheverticaldirectionofunannealedmultilayersampleswereobserved,carriers’transportof annealedsamplescorrespondtoFowler–Nordheim(FN)tunnelingmechanismathighelectricfield.Theopticalbandgapincreaseandopticalabsorptioncoefficientdecreasewiththedecreasingofwelllayerthickness,whichreasultfromquantumsizeconfinementeffect,butthereisnoobviouslychangeintheopicalabsorptioncoefficientandbandgapof nc-Si:H/a-SiC:Hmutilayerfilmwiththedecreasingofbarrierlayerthickness.Inaddition,when the samples were annealedat450℃,theopticalbandgapof mutilayersa