SCANNING TUNNELING MICROSCOPE WITH NOVEL COARSE SAMPLE POSITIONING TECHNIQUE

Abstract

We have constructed a scanning tunneling microscope with coarse positioning device which enables adjustment of the sample to tip distance into operating range of z-piezo element without stretching for each step of sample approach. This new convenient technique is achieved by monitoring sample current during coarse sample approach. The sample to tip distance of several thousand angstroms could be detected directly on oscilloscope. It is considered that sample current is generated by field emission mode of tip operation or field ionization of air molecules due to a potential induced by sawtooth voltage used for driving inertial piezotranslator. In addition, the topographic images of clusters and ultrathin films of carbon on cleaved graphite will be presented.