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AFM( atomic force microscope) 原子力電子顯微鏡. Professor: Kuen-Hsien Wu Student:Syue-An Ceng. Outline. Introduction Basic Principles Application Conclusion References. Introduction. Measurement needs in a vacuum. 需要在真空中測量 Samples must be conductive. 樣品必須導電 - PowerPoint PPT Presentation
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AFM(atomic force microscope)
AFM(atomic force microscope)Professor:Kuen-Hsien WuStudent:Syue-An CengOutlineIntroduction
Basic Principles
Application
Conclusion
ReferencesIntroduction
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Measurement needs in a vacuum.Samples must be conductive.If it is not to be plated with a conductive gold or white gold.Samples can not be a powder or a volatile items.Robert HookeCork cell wallAfter the 1930s, based on quantum mechanics, can grasp and describe the role between atoms.1930 For example, quantum tunneling effect and van der Waals force.Introduction
STM , scanning tunneling microscopyIntroduction
Gerd BinnigCalvin QuateChristoph Gerber
AFM, atomic force microscopyAtomic force microscopy measurements objects mainly van der Waals force, exists between all types of atom.
Basic PrinciplesThe AFM consists of a cantilever with a sharp tip (probe) at its end that is used to scan the specimen surface.AFM
When the tip is brought into proximity of a sample surface,forcesbetween the tip and the sample lead to a deflection of the cantilever according toHookes law.
mechanical contact force, van derWaals forces, capillary forces, chemical bonding, electrostatic forces, magnetic forces (see magnetic force microscope, MFM), Casimir forces, solvation forces, etcTypically, the deflection is measured using a laser spot reflected from the top surface of the cantilever into an array of photodiodes. Other methods that are used include optical interferometry,capacitive sensingor piezoresistive AFM cantilevers.
These cantilevers are fabricated with piezoresistive elementsthat act as astrain gauge. Using a Wheatstone bridge, strain in the AFM cantilever due to deflection can be measured, but this method is not as sensitive as laser deflection or interferometry.Basic PrinciplesImaging modes
Tapping mode
Contact mode
Non-contact mode
Basic PrinciplesTapping mode
Basic Principles
Contact mode
Basic Principles
Non-contact modeBasic Principles
Van derWaals forces
ApplicationMeasuring surface height
Measuring the electrostatic force, magnetic force
Nanolithography
EFM ,Electrostatic force microscopyKPFM ,Kelvin probe force microscope NT-MDT Solver P47 SP-47AFMC-AFM40 X 40 m21.5 2 cm2~ 5 mXY2 nmZ0.07 nm1atm (a) Nanosensors PointProbePlus-RT-NCHRtip curvature radius < 7nm(b) Nanosensors SuperSharpSilicon-NCHRtip curvature radius < 2nm(c) -masch NSC15tip curvature radius < 7nm
AFMC-AFM
ConclusionReferences--
-Atomic force microscopy
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