Quantum dots are artificial atoms in the solid-state occurring in a variety of size and shape, and can be realized in a variety of materials. Electrons and holes in quantum dots are confined in three dimensions typically by the junction of two different materials or by geometric or electrostatic confinement. Unlike other solid-state systems, quantum dots do not have any periodicity, and are characterized by a set of discrete energy levels and localized wave functions analogous to atoms. Quantum dots have found a variety of applications, including light-emitting diodes, photo-detectors, solar cells, quantum computing, logic devices, medicine and biology, to name a few. In this lecture, I will describe how quantum dots are similar to atoms in the periodic table, with the exception that these artificial atoms can be engineered to suit the needs of various applications. Starting from the quantum mechanics of the Hydrogen atom, I will describe two simple models of quantum dots: the particle in a box, and the quantum harmonic oscillator. I will describe experiments that show evidence of shell structure in quantum dots analogous to multi-electron atoms. I will also describe several applications, which rely on the customized properties of quantum dots. Lastly, I will describe how electron transport in a quantum dot differs from that of a solid-state transistor, and introduce the phenomena of Coulomb Blockade.
Birck Technology Center, Room 1001, Purdue University, West Lafayette, IN