TUNNEL CURRENT-CONTROLLED ATOMIC-FORCE MICROSCOPE DESIGNS

The atomic force microscope (AFM) designs described here are based on the high sensitivity of scanning tunneling microscopy (STM) technology. It utilizes short range repulsive contact forces between a small stylus and a sample surface to produce high resolution images of defects and structural features of the surface. An adjacent tunnel gap controls contact forces and provides a very sensitive feedback signal for a Z-direction piezoelectric drive to maintain a constant force value during raster scanning. A STM may serve as an AFM by attaching an AFM adapter. The same piezoelectric drive mechanism, electronics, and recording system can be automatically employed to produce AFM images. This report contains a progression of AFM designs, based on the tunnel current control principle, construction and calibration of AFM levers, AFM applications, and high resolution AFM images.