Improved Scanning Electron Diffraction System

Abstract

An improved transmission scanning electron diffraction system is described. It can make angular measurements comparable with those of photographic instruments, its intensity measurements can have an accuracy of ±0.2% for single traces, ±1% for complete frames, its sensitivity is sufficient to give clear intensity signals from specimens of average thickness equal to an atomic layer, its angular resolving power is 0.23 mrad. Important features of the system are a high productivity rate so that many specimens can be grown within the instrument and examined in a short time; the ability to record diffraction patterns continuously as films are grown by vacuum deposition with growth rate/vacuum values of up to 107 Å sec−1 Torr−1; and ability to scan diffraction patterns in two dimensions. Scan rates depend on the response speed of the X‐Y recorder used and are 10–50 sec for a single trace, 20–60 min for an entire frame from a single crystalfilm. The design of the system is discussed and results from polycrystalline, grain‐oriented, and growingfilms are given to demonstrate its versatility and performance.