高等固体物理-stm afm

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1、专题二：扫描隧道显微学ScanningTunnelingMicroscopy(STM)TheMicroscope“UrgetoSeeMore”ScaleElectronMicroscopy•beamsofelectronsareusedtoproduceimages•wavelengthofelectronbeamismuchshorterthanlight,resultinginmuchhigherresolutionTheTransmissionElectronMicroscope•electronsscatterwhentheypassthroughthinsecti

2、onsofaspecimen•transmittedelectrons(thosethatdonotscatter)areusedtoproduceimage•denserregionsinspecimen,scattermoreelectronsandappeardarkerEM分辨率:约1纳米1931年EbolaTheScanningElectronMicroscope•useselectronsreflectedfromthesurfaceofaspecimentocreateimage•producesa3-dimensionalimageofspecimen’ss

3、urfacefeaturesacolouredscanningelectronmicrograph(SEM)oftheheadofafruitflyNewerTechniquesinMicroscopy•confocalmicroscopyandscanningprobemicroscopy•haveextremelyhighresolution•canbeusedtoobserveindividualatomsConfocalMicroscopy•originallypatentedbyMarvinMinskyin1957•laserbeamusedtoilluminat

4、espotsonspecimen•computercompilesimagescreatedfromeachpointtogeneratea3-dimensionalimageScanningProbeMicroscopy•scanningtunnelingmicroscope–steadycurrent(tunnelingcurrent)maintainedbetweenmicroscopeprobeandspecimen–upanddownmovementofprobeasitmaintainscurrentisdetectedandusedtocreateimageo

5、fsurfaceofspecimenTheScanningTunnelingMicroscopeworkslikearecordplayer…分辨率:约0.01纳米1981年APL40,178(1982)TheNobelPrizeinPhysics1986ErnstRuska(1906-1988)"forhisfundamentalworkinelectronoptics,andforthedesignofthefirstelectronmicroscope”GerdBinnigHeinrichRohrer(1947-)(1933-)“fortheirdesignofthe

6、scanningtunnelingmicroscope"ScanningTunnelingMicroscope(STM)OmicronLT-UV-STM,USTC’98STM的基本原理-量子隧穿Chen,C.J.InIntroductiontoScanningTunnelingMicroscopy;OxfordUniversityPress:NewYork,1993;p3.Inclassicalmechanics,theenergyofanelectronmovingina2potentialU(x)canbeshownbypxUxE2mTheelectronhas

7、nonzeromomentumwhenE>U(x),butwhenEU),therearetwosolutions,ikx2mEU(x))0(e,wherekHowever,intheclassicallyforbiddenregion(E