CBED and CBIM from semiconductors and superconductors

Abstract

The applications of Convergent Beam Electron Diffraction (CBED) and Convergent Beam Imaging (CBIM) to the study of semiconductors and superconductors are reviewed. These applications include the use of well established methods such as point and space group determinations (with YBa 2 Cu 3 O 7−δ ceramic superconductors being demonstrated to be Pmmm in spite of a very high density of symmetry-breaking defects) and lattice parameter determinations in strained crystals (where CBED allows us to observe the small monoclinic distortions present in partially relaxed GeSi strained epilayers). The use of CBIM is demonstrated for studies of strains in GeSi-Si strained-layer superlattices and interface between Si and SiO 2. Finally, CBED is also shown to have application in the study of local compositions (on a scale which is significant both in modern semiconductor devices and in the new ceramic superconductors), and two methods for microanalysis are demonstrated: zone-axis critical voltage effects are studied in the ceramic superconductor La 2−x Sr x CuO y , as a function of y and HOLZ branch structures are studied in Al x Ga 1−x as a function of x.