Atomic Force Microscopy

• AFM introduction

• AFM machinery

• Cantilevers

• Contact models / Van der Waals forces

• Contact mode imaging

• Lateral forces

• Force modulation

Original Idea of AFM

One year later: Atomic Resolution

Modern AFM• Common displacement detection methods

– Beam bounce

– Interferometric

– Piezoresistive

• Generally characterized by minimum detectable

displacement per squareroot Hz (mechanical

displacement noise level)

Also readAlso read : : http://www.physikinstrumente.com/en/products/piezo_tutorial.phphttp://www.physikinstrumente.com/en/products/piezo_tutorial.php

A quick comparison

All methods have applications depending on their strengths and weaknesses

PZR

Modern cantilevers• Generally micromachined out of silicon and silicon nitride

Copyrighted material, used for educational purposes

Tip-sample Contact • Hertzian contact theory is a good starting point

Elasticity of materials

Contact Mode Imaging

Contact mode imaging

• Contact force

– Think about contact area and pressure

• Modifications to tip and sample

• Easier (no harmonic oscillator response to

deal with) and higher stability

• Subject to DC drifts