Polytypisme du carbure de silicium: diffraction électronique et simulation optique

Abstract

Optical simulation methods are applied to the determination of the Ramsdell sequence of silicon carbide polytypes. A new technique to produce two-dimensional models allows the simulation of intermediate and long-period polytypes. Punched computer cards are stuck together and the model so formed is photographically reduced. Simulations of 6H, 15R and 27H SiC polytypes are shown for demonstration. The `zigzag' sequence for a 51-layer polytype is identified by comparison between its RHEED pattern and the laser diagrams of 51Ra and 51Rb optical models.