We have heard a lot about the exciting new materials being used in microelectronics, and I would like to describe some experiments making use of in situ electron microscopy to try to understand the mechanisms of the reactions that these materials undergo during deposition and processing. I will discuss experiments in which we carry out one of these reactions within an electron microscope and record the effect on the specimen in real time. We then use measurements from the recordings to analyze the reaction mechanism in a quantitative way. In this article, I will cover two types of experiments. First, I will describe experiments in which we examine the motion of surface and interface steps during reactions, and I will discuss how that information allows us to determine reaction mechanisms. In this context, I will consider silicon oxidation and silicide formation. In the second type of experiment, we look at how surface morphology changes during reactions. In particular, we will try to understand the growth mechanism of “quantum dots,” which are becoming important for some novel microelectronic applications. After discussing these results, I will describe our attempts to extend the technique of in situ electron microscopy to look at systems other than the solid—solid or gas—solid interface.

Exactly 50 years ago, E.W. Müller became the first person to observe single atoms, with the aid of the field-ion microscope (FIM). In 1967, with John Panitz and S. Brooks McLane, Müller's invention of the atom probe meant that, in his words, “We can now really deal much more intimately with the individual atoms which we encounter, since we know their names.” By combining position-sensitive detection with the time-of-flight mass spectrometry of single atoms in the atom probe, Cerezo and co-workers in the late 1980s built an instrument capable of reconstructing the three-dimensional (3D) atomic distribution of elements present in a material. The instruments that are capable of microanalysis at this level, called generically 3D atom probes (3DAPs), were the subject of two articles published in MRS Bulletin in 1994. In this article, we review some of the progress in the field since that time, in particular, the expansion of the range of materials problems that can be addressed by this powerful technique.

Organic thin films have been studied for their properties as active optoelectronic materials for at least 50 years. Yet, until recently, they have failed to make a significant impact in the commercial world. However, display products based on organic light emission are now available commercially, indicating that a major change in the acceptance of organic optoelectronics is in the offing. I would like to discuss some of the reasons for these developments from an engineering perspective.

Scientific consideration of how to scale electronics down to the molecular level started in the mid-1970s. Unfortunately, at the time, researchers did not have the adequate analytical tools to perform the experiments. That has changed drastically, and therefore interest in this field has been renewed, especially over the last few years.

Since the discovery of high-Tc superconductors (HTSs), especially the Bi-based oxide superconductors (Bi-HTSs) in 1989, much effort has been concentrated on the fabrication of Bi-HTS wires and tapes. Bi-HTSs are interesting materials from the viewpoint of practical applications. One of the interesting applications of Bi-HTSs is the cryogen-free conduction-cooled magnet. Besides having a high transition tem- perature (Tc), Bi-HTSs have high upper critical fields (Bc2) or high irreversibility fields (Birr) at temperatures below ∼30 K. Because ∼30 K can be efficiently main- tained by a cryocooler, a Bi-HTS magnet cooled with a cryocooler has great potential in many technological applications. Another promising application of Bi-HTSs is the high-field magnet. When the temperature is reduced to ∼5 K, Bi-HTSs show a much higher Bc2 or Birr than do conventional metallic superconductors (low-temperature superconductors, LTSs) such as Nb3Sn. This indicates that Bi-HTSs also have great potential for use in a high- field superconducting magnet if the magnet is operated at low temperature.