Development and performance of the nanoworkbench: A four tip STM for conductivity measurements down to submicrometer scales

Abstract

A multiple-tip ultrahigh vacuum (UHV) scanning tunneling microscope (MTSTM) with a scanning electron microscope (SEM) for imaging and molecular-beam epitaxy growth capabilities has been developed. This instrument (nanoworkbench) is used to perform four-point probe conductivity measurements at μm spatial dimension. The system is composed of four chambers, the multiple-tip STM∕SEM chamber, a surface analysis and preparation chamber, a molecular-beam epitaxy chamber, and a load–lock chamber for fast transfer of samples and probes. The four chambers are interconnected by a unique transfer system based on a sample box with integrated heating and temperature-measuring capabilities. We demonstrate the operation and the performance of the nanoworkbench with STM imaging on graphite and with four-point-probe conductivity measurements on a silicon-on-insulator (SOI) crystal. The creation of a local FET, whose dimension and localization are, respectively, determined by the spacing between the probes and their position on the SOI surface, is demonstrated.