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We describe a simple, yet phenomenologically very different, low-temperature modification to the conventional metal–organic chemical vapor deposition. It has been applied to the epitaxy of hexagonal-phased Bi2Te3/Sb2Te3 superlattices on zinc-blende GaAs substrates. The modification enables a two-dimensional, layer-by-layer, epitaxy instead of a three-dimensional islanded growth. Therefore, this approach is of generic importance to the epitaxy of many electronic and magnetic materials and their superlattices. High-resolution transmission electron microscopy studies indicate that the interface between the GaAs substrate and Bi2Te3 film is qualitatively defect free and that periodic structures are formed in the Bi2Te3/Sb2Te3 superlattices, with one of the individual layers as small as 10 Å. Such ultra-short-period superlattices offer significantly higher carrier mobilities than their respective solid-solution alloys, apparently due to the elimination of alloy scattering and the minimal effects of random interface scattering on carrier transport. This represents one of the successful observations of enhanced carrier mobilities in monolayer-range superlattices.

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SUMMARY Electron‐induced radiation damage can cause errors in interpreting electron micrographs. Radiation damage is distinguished from contamination (polymerization of hydrocarbons) and etching (radiolysis in the presence of water), both of which can be controlled by a proper specimen environment in the microscope. While temperature has little effect on the primary interactions of fast electrons with matter, most secondary radiation‐damage processes are temperature dependent. Because damage mechanisms differ so greatly among materials, there is no simple factor by which specimen stability is improved as a function of temperature (some cases improve fivefold, others improve 100‐fold). While some specimens are stable to almost arbitrarily high doses, some tests reveal damage at 1 e/nm2. This paper surveys damage rates and temperature dependencies of various materials as a guide for future electron microscopic studies of organic specimens.