High-resolution transmission electron microscopy of heterostructures

• Published in: Solid-state electronics Vol. 37; no. 4; pp. 1045 - 1052
• Main Author: Cerva, H.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Oxford Elsevier Ltd 01.04.1994; Elsevier Science
• Subjects: Condensed matter: structure, mechanical and thermal properties; Electron, ion, and scanning probe microscopy; Exact sciences and technology; Physics; Structure of solids and liquids; crystallography; Heterojunctions; Transmission electron microscopy; Quantum wells; Superlattices; Structural analysis
• ISSN: 0038-1101; 1879-2405
• DOI: 10.1016/0038-1101(94)90354-9

Chemical information on a near-atomic scale may be obtained from high-resolution transmission electron microscope (HREM) images. This requires first a distinct contrast difference in the adjacent semiconductor materials in a particular projection direction for a wide range of objective lens defoci and specimen thicknesses for the given microscope parameters (acceleration voltage, spherical aberration constant). Second, the image must contain Fourier components which behave almost linear with layer composition. The contrast formation in the systems Al/GaAs and Si/Ge, where such conditions may be found and which are representative for amplitude and phase contrast respectively, is discussed. The method of chemical lattice imaging is applied to Al x Ga 1− x As structures and reveals differences in the abruptness of GaAs on Al x Ga 1− x As and Al x Ga 1− x As on GaAs interfaces. Selected area diffraction systems with high accuracy.