One of the ultimate aims of "nanostructure engineering" has been to develop structures containing as few as one electron. Recently, the key difficulties in the last few years in studying the physics of nanostructures have not been in tailoring small structures; instead they have been in the measurement of the minuscule signals emanating from a system containing only a few electrons. In this regard, new technique has been developed for the detection of minute amounts of electrical charge. This has allowed for a new high resolution spectroscopic tool known as "Single-Electron Capacitance Spectroscopy" (SECS). The results so far indicate that this technique should become widely applicable to the study of few electron systems in nanostructures, single defects, and single impurity atoms. The central theme of the work to be conducted here is the development and extension of the SECS method to study a variety of basic physics and materials problems. A top-loading dilution refrigerator and high field magnet system will be of central utility in these measurements. The refrigerator proposed here will allow rapid cooling of samples and can accommodate a variety of different experiments through the use of separate measurement probes.
