Indirect Excitons

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NON-TECHNICAL ABSTRACTThis individual investigator award supports a project directed towards experimental studies of fundamental optical and electronic properties of structures made of thin layers of semiconductors. A special design of the structures on a length scale of a billionth part of a meter allows the creation of new quasi-particles called indirect excitons. The indirect excitons are unique because they can be cooled down to ultralow temperatures. Furthermore, the indirect excitons are unique because they can be electronically controlled like electrons in electronic devices and can emit optical signals. The project is directed towards increasing our understanding of the physics of ultracold indirect excitons. The understanding gained through this research may lead to the exciting possibility of developing advanced devices that make use of electronic as well as optical properties, i.e. optoelectronic devices. Undergraduate and graduate students will be involved in this project and will have the opportunity to perform research on the cutting edge of contemporary physics. The training they receive will prepare them for employment in high-tech industries across the nation.TECHNICAL ABSTRACTThis individual investigator award supports a project directed towards experimental studies of cold indirect excitons and cold electron-hole plasma in coupled quantum well semiconductor structures. Indirect excitons are formed by electrons and holes confined in spatially separated quantum well layers. Due to their long lifetime, indirect excitons can cool below the temperature of quantum degeneracy. This gives an opportunity to study cold excitons. Due to their long lifetime, indirect excitons can travel over large distances before recombination. This gives an opportunity to study exciton transport. Furthermore, indirect excitons are dipoles and their energy can be controlled by voltage. This gives an opportunity to create a variety of potential landscapes for indirect excitons and use them as a tool for studying cold excitons – cold composite bosons in materials. Studies include transport of cold indirect excitons in basic mesoscopic devices – quantum point contacts, and cold electron hole plasma in separated electron and hole layers. The research is performed by students and is integrated with education. The potential impact of the project is in development of knowledge in condensed matter physics and increase of fundamental understanding of optical and electronic properties of materials.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.