EXPERIMENTAL EVALUATION OF A SCANNING TUNNELING MICROSCOPE-MICROLENS SYSTEM

This paper presents the results of the first successfully fabricated scanning tunneling microscope (STM) aligned field emission (SAFE) microsource. SAFE sources have been shown to produce 2-3 orders of magnitude improvement in brightness over conventional field-emission sources. Lens electrodes were fabricated from 1-mu-m thick silicon membranes by electron-beam lithography and reactive-ion-beam etching. Two-element microlenses were tested in an ultrahigh vacuum (UHV) chamber with a piezo mounted tungsten tip and a dual feedback system. The sources demonstrated stable emission for periods of hours at beam energies of up to 1 kV. Measurement of the virtual source position showed good agreement with calculated values.