Synthesis, properties and applications of self-assembled quantum structures

Continued miniaturization of electronic devices is the primary cause for improvement of both speed and packing density. At this time, there is a great demand for nanostructured devices, that are essentially quasi one-dimensional (quantum wires) or quasi zero-dimensional (quantum dots), which promise vastly improved speed and power characteristics.; In this dissertation, we employed electrochemical self-assembly for the fabrication of highly periodic two-dimensional arrays of metallic and semiconductor quantum dots or wires. Self-assembly is an attractive alternative to nanolithography because of high throughput and low cost. The structural analysis of the self-assembled quantum structures was carried out by AFM, TEM and SEM to reveal information about sizes, shape and periodicity. Additional information about quantum mechanical confinement of carriers in these structures was provided by Raman spectroscopy.; We discovered two new phenomena in self assembled CdS and ZnSe quantum dots. The first is an intrinsic bistability in the transport (I-V) characteristics that can be exploited to realize a non-volatile quantum dot memory (patent applied for), and the second is a strong infrared photoresistance that can be used in a novel “inverse” infrared photodetector (patent disclosure made to University of Nebraska). Finally, we also found signatures of Coulomb blockade and Coulomb staircase (at room temperature) in quantum dots and wires which holds out the promise that these structures may find applications in single-electron-transistors and other novel nanodevices.