The goal of this research program is to fabricate semiconductor devices small enough that new quantum-mechanical phenomena can be observed. Silicon MOSFET's will be produced with narrow 25 nm width gates. The conductance of these devices will be studied at low temperatures and high magnetic fields. Recent results indicate that electron-electron interactions may be altered in such confined geometries. To better understand the nature of the high-conductance state observed at high magnetic fields, a variety of split-gate devices will be fabricated with various widths but with constant ratio of length to width. By keeping this aspect ratio constant on passing from very narrow to wide devices, the researchers expect to observe the evolution of the high-field state in the confined geometry into the quantum Hall state. In this way, the dependence of the properties of the high field state on width can be measured. Experiments on the magnetic field dependence of the step-gate devices will be carried out of the Francis Bitter National Manget Laboratory.
