薄膜材料的表征方法(二)课件.ppt

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1、薄膜材料的表征方法（二）ANALYTICALTECHNOLOGIESOFTHINFILMS（2）谭永胜2004.11.20AbstractElectronicbeamanalytictechniques.Lowenergyelectrondiffraction(LEED)andReflectionhighenergyelectrondiffraction(RHEED).Scanningelectronmicroscopy(SEM)andTransmissionelectronmicroscopy(TEM).Electronicbea

2、manalytictechniquesPropertiesofelectrons:Aninelasticmeanfreepath(MFP)ofafewtenthofnm.Electronsareeasilyfocusedintobeamsandtheenergymaybevaried.Electronsareefficientlydetectedandcounted.Electronsmaybeanalyzedangularandenergydistribution.Electronsdisappearfromthevacuumsy

3、stemafterbeingusedforanalysis.ElectronicbeamanalytictechniquesTheinteractionofanincidentelectronbeamwithasolidsample.ElectronicbeamanalytictechniquesEnergydistributionofthesecondaryelectrons.Lowenergyelectrondiffraction(LEED)AccordingtothedeBroglierelation,thewavelengt

4、hoftheelectronsisgivenby:λ=h/pWhentheelectronsareacceleratedbyavoltageV,thekineticenergyofelectronsiseV,andtheelectronmomentumcanbeexpressedbyp=(2meV)1/2Thustheelectronwavelengthisdeterminedby:λ=h/(2meV)1/2=(150.4/V)1/2.LEED:E<1000eVRHEED:5-100keVLowenergyelectrondiffr

5、action(LEED)SchematicapparatusofLEED.Lowenergyelectrondiffraction(LEED)Atomicarrangementonsurface.Lowenergyelectrondiffraction(LEED)LEEDpatternsofSicleansurfaces.Lowenergyelectrondiffraction(LEED)Reflectionhighenergyelectrondiffraction(RHEED).SchematicdiagramofRHEEDopt

6、ics.Reflectionhighenergyelectrondiffraction(RHEED).Reflectionhighenergyelectrondiffraction(RHEED).TheintensityofspecularRHEEDbeamvariedwiththesurfacecoverage.Reflectionhighenergyelectrondiffraction(RHEED).Thearrow-likestreaks.Reflectionhighenergyelectrondiffraction(RHE

7、ED).ConclusionPrinciple:(a):thedeBrogliematerialwaveofelectrons.(b):Braggdiffraction.Properties:(a):surfaceanalysis.(b):RHEEDiswellsuitedforsitumonitoringinMBE.(c):needUHV.Scanningelectronmicroscopy(SEM)Theprincipleoflightmicroscopyandelectronmicroscopy.Scanningelectro

8、nmicroscopy(SEM)Scanningelectronmicroscopy(SEM)Scanningelectronmicroscopy(SEM)Scanningelectronmicroscopy(SEM)Scanning