Novel Optical Investigations of Spin-Dependent Effects in Semiconductor Nanostructures

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This is an Information Technology Research Proposal (ITR). Until recently, an intrinsic property of electrons, their spin, has been overlooked in potential applications in electronics. Understanding and manipulating spin in appropriate semiconductor structures offers promise for entirely new types of future "spintronic" devices and for producing elements of quantum computers. "Spintronic" devices are non-volatile, consume less power, and can be faster than conventional electronic devices that are based on the charge of the electron. This project will focus on investigating the complex states of electrons and holes and their interactions with the local environment in semiconductor quantum structures that have potential for application in spin-based devices which ultimately might find their way into future quantum spin based computers. An array of optical techniques will be used to probe spin-related effects in semiconductor nanostructures. The project will couple extensive experimental investigations with theoretical calculations and predictions. Three graduate students, one undergraduate student and one or more high school physics teachers will be involved in these projects. Results are expected to reveal new physics and bring improved understanding to issues that will be important for implementing future generations of devices for information technology. This is an Information Technology Research proposal (ITR). Until recently the carrier spin has been overlooked in electronic devices. Understanding and exploiting carrier spin in semiconductors offers promise for spintronic devices, which are non-volatile, consume less power, and can be faster than devices based on manipulation of carrier charge. This project couples experimental and theoretical research directed at understanding and manipulating spins in semiconductor structures. The detailed nature of electronic states of neutral and spin-singlet/-triplet charged excitons in GaAs/AlGaAs lateral fluctuation quantum dots will be investigated with the goal of understanding their role in possible implementation of quantum bits. The spin states of carriers in spin-injection devices will be probed with the goal of understanding the effects of lattice vibrations, band structure, phonons, interfaces and diffusion distances on the degree of spin polarization. Polarized photoluminescence (PL) and PL excitation spectroscopies combined with optically detected resonance (ODR) spectroscopy of free electrons and holes, and internal transitions of excitons will be employed in these studies. Three graduate and one undergraduate students, one or more high school physics teachers will be involved in these projects. Results are expected to reveal new physics and bring improved understanding to issues that are important for future information technology applications.