Automatic bias-reduction controller for a scanning tunneling microscope.
In order to protect the sample and the tip against current transients in a scanning tunneling microscope, which in most cases damages the scanned surface and the tip, when using a bias higher than 1V, we have designed a simple and low-cost circuit that limits the tunneling current. During the evolution of the current transient, when the current exceeds a pre-determined value, a fast feedback control mechanism immediately reduces the bias and prevents the current transient from developing. In addition, we designed a fast pre-amplifier that works with this controller. We have shown that this mechanism provides a better scanning image compared to a system without such a mechanism.
Flaxer
Eli
E
Afeka - Tel-Aviv Academic College of Engineering, 69107 Tel-Aviv, Israel. flaxer@afeka.ac.il