Electrical Applications of AFM: Current Imaging of Nano Devices

Tom Kopley, PhD & Maozi Lui PhD
Santa Clara Meeting 2008

Scanning Gate Microscopy (SGM) is a powerful technique for investigating electrical properties of nanoscale devices. Previous studies of SGM on carbon nanotubes field-effect transistors (CNTFETs) has shown that the conductance along nanotubes varies, most likely due to static charge in the insulating substrate underneath the nanotubes. SGM has always been done in liftmode, which limits lateral resolution. We have developed a variation of SGM that is used in intermittent contact mode (IC-SGM), in which the SGM signal is obtained simultaneously with topography and phase images. IC-SGM is easier to implement and produces better lateral resolution, because the tip-sample interaction occurs when the tip is very close to the sample. We also show that the tip does not inject charge into the nanotubes when it touches the nanotube. Varying the set point shows evidence for conductance changes due to CNT deformation or redistribution of surface charge.

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Related Application Notes

Scanning Microwave Microscopy

Introduction to Scanning Microwave Microscopy