The focus of this research program will be the transport characteristics and device applications of heterostructured compound semiconductors and intermetallics. Two distinct intermetallic systems, the transition metal aluminides (e.g. NiA1) and the rare earth monopnictides (e.g. ErAs) can be incorporated epitaxially in compound semiconductor (e.g. A1GaAs) to fabricate multilayered semiconductor/metal/semiconductor heterostructures. These novel composites represent a revolutionary advancement in the materials research. They also provide the device physicists with powerful new opportunities for engineering unique devices with transport properties which are difficult or impossible to achieve in all-semiconductor structures. Previous work has shown that for sufficiently thin layers, these semiconductor clad intermetallics exhibit two- dimensional quantum size effects in what is essentially a metallic quantum well. It has also been shown that these effects can be exploited to fabricate quantum transistors operating at room temperature. These transistors operate in a hidden-field effect (HFET) mode where the electrodes are stacked in a vertical gate/drain/source structure. The metallic drain screens (hides) the gate potential from the drain-source junction yet the gate-drain field modulates the energy of the resonance states in the metal which in turn influences the drain-source junction tunneling current. These channelless vertical transistors can be readily scaled down to the minimum available process linewidths, and could therefore be attractive for future high density integrated circuits.
