Application of a scanning tunneling microscope to field emission studies

The authors present a scanning tunneling microscopy (STM) of a novel design, which has been integrated into their field-emission scanning microscope. It has been developed for large-area scans (50 mu m*50 mu m) with site selection under scanning electron microscopy (SEM) control and subsequent zooming to high-resolution STM scans. The authors show that significant images of relatively large areas can be obtained. Initial field-emission scans indicate that topography can be distinguished by the field-emission behavior of a surface. The lowest beta values observed on an arbitrarily chosen spot on a niobium samples were on the order of 1.6. The remaining difference from the ideal case of beta =1 is unexplained.>