The interpretation of high-resolution electron micrographs of materials with wurtzite structure has been investigated in a comparative study of the 〈1120〉-oriented semiconductors cadmium selenide (CdSe) and cadmium sulphide (CdS). Trends in scattering and imaging behaviour are shown to be similar to those exhibited by the related (cubic) sphalerite structure, in particular, the implications for image formation of the breakdown of Friedel's law under dynamical scattering conditions and the importance of both low- and high-resolution imaging for the determination of crystal thickness, defocus and polarity. Experimental images of 〈1120〉 CdSe have been recorded at 100 kV and 400 kV. A major limitation to image interpretation is shown to be the extreme sensitivity of materials with the wurtzite structure to the effects of beam or crystal misalignment due to the presence of dynamically forbidden reflections (Gjønnes-Moodie lines) in the projection investigated.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Atomic and Molecular Physics, and Optics