Electronic, Optical, and Vibrational Properties of IV - VI Semiconductor Nanocrystals

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9321259 Wise Technical abstract: It is proposed to investigate the properties of semiconductor nanocrystals which exhibit strong quantum confinement of electrons, holes and excitons. Nanocrystals of the semiconducting lead chalcogenides provide unique access to the strong-confinement regime. The electronic structure, the vibrational properties, and the coupling of the electronic and vibrational states of these nanocrystals will be investigated with Raman and far-infrared spectroscopies as well as continuous wave, nanosecond and femtosecond optical techniques. This research will provide detailed information about the importance of Coulomb interactions under conditions of strong confinement of charge carriers. Non-technical abstract: Solid structures which confine electrons to dimensions on the order of atomic sized dimensions have properties which differ drastically from those of the corresponding bulk crystals. The goal of this project is to determine the electronic and optical properties of nanostructures made of the lead salts (such as lead sulfide), where the effects of confinement should be greater than in most other materials. The unique features of the lead salts are expected to lead to nonlinear optical properties approximately 1000 times stronger than those of previously investigated nanostructures. The potential applications of such strongly optically nonlinear materials is in optical information processing. ***