A STUDY OF DIRECTLY RECORDED RHEED AND BKD PATTERNS IN THE SEM

A new method of recording reflection high-energy electron diffraction (RHEED) patterns in the scanning electron microscope (SEM) is discussed. The method involves direct recording of RHEED patterns on photographic film positioned in the vacuum of the chamber at approximately 10(-7) Torr, using a probe diameter approximately 20 nm and a working distance approximately 12 mm. RHEED patterns obtained from bulk as-received silicon and GaAs surfaces were seen to exhibit Kituchi bands, continuous circles of intensity and, in some cases, specular reflections. The technique was used to investigate thin GaAs capping layers deposited on GaA1As. An account is also given of the application of backscatter Kikuchi diffraction patterns (BKDP) in the SEM to point group and space group determinations. Using the technique, a space group Fd3barm was determined for silicon. Theoretically calculated and experimentally obtained intensity profiles were used to investigate contrast variations across the hhO systematic row of reflections in BKDPs from silicon. The geometrical differences between BKDPs and RHEED patterns are also discussed.