A High-Resolution Scanning Transmission Electron Microscope

Abstract

A simple scanning transmission electron microscope has been built using a field-emission electron source, a new electron gun, and one lens to produce a high-contrast picture with 30 Å resolution. The final spot size is limited by the properties of the lens, in the same manner as a conventional transmission microscope. The field-emission tip requires a pressure below 10−9 Torr for stable operation and can have a lifetime of several months. The intensity of the source is such that high-quality pictures can be obtained in 10 sec. Specimen contamination or damage is small, as would be expected in view of the good vacuum conditions. The theory and design of the instrument are discussed, and experimental results are shown.