Kikuchi Patterns Observed by New Astrodome RHEED

A new reflection high-energy electron diffraction (RHEED) apparatus equipped with a hemispherical fluorescent screen upon a sample surface has been constructed. We call it astrodome screen, namely, the apparatus is named as astrodome RHEED. For the observation of Kikuchi pattern in RHEED experiment, the astrodome screen is effective because of the relatively short escape depth of Kikuchi electrons arising in bulk. Diffraction patterns have been observed in the astrodome screen for Si(111)7 × 7 clean surface, and the glancing angle and the acceleration voltage dependences were investigated. It has been found that some circular patterns exist in the Kikuchi patterns. The circular patterns are considered to be responsible for one-dimensional diffractions from certain atomic rows in bulk. The observed Kikuchi patterns and circular patterns are calculated using simple kinematical theory and a good agreement between the experimental and calculated results has been obtained. [DOI: 10.1380/ejssnt.2006.118]