学科分类
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14 个结果
  • 简介:Geepilayersofdifferentthicknessesaregrownbymolecular-beamepitaxywithSbasasurfactantonSI(100)substrates,X-raydiffractionillustratesthattheseGethinfilmsarepartiallystrained.andthestrainsdecreasegraduallywithincreasingepilayerthickness,RamanspectrarevealadownwardshiftoftheGe-Gemodepeakastheepilayerthicknessincreases.Intheregionsofhighstrain,therelationshipbetweentheRamanshiftofthismodeandthestraininthepartiallyrelaxedsamplesisconsiderablydifferentfromthelinearrelationshipreportedbefore,whichismainlyattributedtothespatialconfinementeffectofphononsinananocrystal.

  • 标签: 镓外延薄膜 硅衬底 形变研究
  • 简介:TheballmillingofFe-24MnandFe-24Mn-6Simixedpowdershasbeenperformedbythehighenergyballmillingtechnique.ByemployingX-raydiffractionandMoessbauermeasurements.Theccmpositionevolutionduringthemillingprocesshasbeeninvestigated.TheresultsindicatetheformationofparamagneticFe-MnorFe-Mn-Sialloyswithametastablefccphaseasfinalproducts.whichimplythattheFeandMnproceedaco-diffusionmeenanismthroughthesurfaceoffragmentedpowders.Thethermalstabilityandcompositionevolutionoftheas-milledalloyswerediscussedcomparingwiththebulkalloy,.

  • 标签: 合金 FE-MN FE-MN-SI 穆斯鲍尔效应
  • 简介:Amorphoussilicon(a-Si),nanocrystallinesilicon(nc-Si)andhydrogenatednanocrys-tallinesilicon(nc-Si:H)filmswerefabricatedbyusingchemicalvapordeposition(CVD)system.Thea-Siandnc-Sithinfilmswereirradiatedwith94MeVXe-ionsatfluencesof1.0×1011ions/cm-2,1.0×1012ions/cm-2and1.0×1013ions/cm-2atroomtemperature(RT).Thenc-Si:Hfilmswereirradiatedwith9MeVXe-ionsat1.0×1012Xe/cm-2,1.0×1013Xe/cm-2and1.0×1014Xe/cm-2atRT.Forcomparison,mono-crystallinesilicon(c-Si)sampleswerealsoirradiatedatRTwith94MeVXe-ions.AllsampleswereanalyzedbyusinganUV/VIS/NIRspectrometerandanX-raypowderdiffractometer.Variationsoftheopticalband-gap(Eg)andgrainsize(D)versustheirradiationfluencewereinvestigatedsystematically.Theobtainedresultsshowedthattheopticalband-gapsandgrainsizeofthethinfilmschangeddramaticallywhereasnoobservablechangewasfoundinc-SisamplesafterXe-ionirradiation.Possiblemechanismunderlyingthemodificationofsiliconthinfilmswasbrieflydiscussed.

  • 标签: NC-SI H薄膜 离子辐照 A-SI 光学带隙 改造
  • 简介:TherearetwotpyesofphasetransformationsinFe-MnandFe-Mn-Sialloyswhenthetemperatureisdecreased,γ(fcc)→ε(hcp)martensitictransformation(MT)andparamagnetic-antiferromagnetictransition(AMT)ofγphase.Fromthethermodynamicpointofview,theformerusuallyappearsinaslightlyhighertemperaturerangethanthelatterbecauseifisgenerallyacceptedthatthemagnetictansitionhasasuppressingeffectonthethermallyinducedεmartensite(Satoetal.,1984.,BogachevandZvigintzeva,1976;Murakamietal.,1987:Yangetal.,1992)GartsteinandRobinkin(1979)eventhoughtthattheγ-εtransformationshouldbeterminatedbelowNeeltemperature(TN)duetothedecreaseoffreeenergyarisingfromtheAMTofγphase.However,someexperimentalresultshaeindicatedtheformationofεphasebelowT(LiandWayman,1994:Fujimori.1966).Inthepresentwert.thebehavorofγ-εtransformationbelowTNwasfurtherinvestigatedbyclectricalresistancemeasurements.

  • 标签: 相变 FE-MN-SI合金 γ(fcc)-ε(hcp)
  • 简介:MoleculardynamicssimulationsareperformedtoinvestigateCF3continuouslybom-bardingtheamorphoussiliconsurfacewithenergiesof10eV,50eV,100eVand150eVatnormalincidenceandroomtemperature.TheimprovedTersoff-Brennerpotentialswereused.Thesimu-lationresultsshowthatthesteady-stateetchingratesareabout0.019,0.085and0.1701for50eV,100eVand150eV,respectively.Withincreasingincidentenergy,atransitionfromC-richsurfacetoF-richsurfaceisobserved.IntheregionmodifiedbyCF3,SiFandCFspeciesaredominant.

  • 标签: 分子动力学模拟 CF3 蚀刻率 硅刻蚀 机理 表面能量
  • 简介:用X射线摇摆曲线和掠入射衍射、透射电镜、原子力显微镜等实验技术研究了MBE方法生长的Si缓冲层生长温度对SiGe/Si异质结结构的影响。结果表明,所研究的SiGe外延层晶格发生完全弛豫,但表面粗糙度和界面失配位错随Si缓冲层的生长温度而变化,最佳生长温度为450℃;缓冲层晶格应变是达到高质量SiGe外延层的主要原因。

  • 标签: Si缓冲层 生长 温度 SiGe外延层结构 X射线 晶格
  • 简介:通过同步X光荧光(SXRF)成分分析,定性地研究了在0.5atm、0.6atm、0.7atmAs压下1150℃进行退火处理后衬底化学与比的变化。结果表明:控制As压可以改变化学配比,在足够As压下的高温退火将改善化学配比均匀性。

  • 标签: 高温退火 半绝缘GAAS As压 化学配比 X光荧光分析 砷化镓
  • 简介:利用同步辐射掠入射和常规X射线衍射,对Si(001)衬底上自组织生长Ge量子点组分和应变进行了研究。结果表明量子点为50%应变驰豫的GeSi合金量子点,其Ge组分为0.55。此外在掠入射X射线衍射Si(220)峰的高角旁观察到另外一个峰,对应于量子点周围衬底中由成岛引起的压应变。

  • 标签: Si(001)衬底 自组织生长 Ge 量子点 组分 应变
  • 简介:低温下用MBE方法生长了Ge/Si超晶格。X射线近边吸收限精细结构研究表明,Ge与Si再Ge/Si界面处存在化学混合。X射线反射及横向散射研究表明,Ge亚层上下表面的粗糙度呈反对称,下表面大的粗糙度来源于Ge向Si亚层中扩散形成SiGe混合组分结构:这种组分结构可以用一平均成份的SiGe合金层加以拟合,从而使得各亚层均有一个合理的粗糙度。旋转样品进行的X射线散射研究表明,这种SiGe的混合是各向同性的,这与透射电子显微镜的研究结构相一致。

  • 标签: Ge/Si超晶格 界面结构 X射线 粗糙度 纳米结构 光电特性
  • 简介:利用同步辐射(BSRF)漫散射站四圆衍射仪,对SiC体单晶的结构进行了判定以及对利用常压化学气相沉积(APCVD)生长的3C-SiC/Si(001)中的孪晶及含量进行了分析。六方{10-15}极图证明了该SiC单晶为6H(H为Hexagonal的缩写)结构。对3C-SiC外延薄膜,Φ扫描证明了3C-SiC外延生长于Si衬底上,外延取向关系为:(001)3C-SiC//(001)Si,[111]3C-SiC//[111]Si。3C-SiC的{111}极图在x=15.8°出现了新的衍射,采用六方{10-10}极图以及基体倒格点111、孪晶倒格点002的Mapping分析了x=15.8°处产生的衍射为3C-SiC孪晶所致,并利用ω扫描估算了孪晶的含量约为1%。

  • 标签: X射线四圆衍射仪 SiC体单晶 3C-SiC外延层 孪晶 APCVD 碳化硅