This project is directed toward the synthesis, processing, and characterization of GaAs/GaInAs/GaInNAs quantum-well and quantum-dot p-i-n heterostructure materials for application in high-efficiency photovoltaic devices. Fundamental issues in optimization of epitaxial heterojunction interface quality and controlled formation of self-assembled quantum dot structures by molecular-beam epitaxy are explored in the context of photovoltaic devices but with broad-ranging material and device implications. In addition, the basic physics and performance potential of quantum-well/dot and related photovoltaic device concepts is examined and employed as a driver for exploration of specific materials issues. Integration of metal and dielectric nanostructures with semiconductor heterostructures, which is expected to enable key advances in engineering of photon propagation behavior in semiconductor heterostructures, is also investigated. Ultimately, it is anticipated that the advances in materials physics enabled by the project will contribute substantially to the development of highly efficient quantum-well and quantum-dot based solar cells, which have been predicted theoretically to enable power conversion efficiencies well in excess of those attainable using more conventional solar cell technologies. This work entails an international collaborative effort between researchers at the University of California, San Diego (UCSD) and at the University of Karlsruhe in Germany. Researchers at Karlsruhe, led by Dr. Daniel Schaadt, focus on epitaxial material growth and optimization, while UCSD researchers focus on materials processing, characterization, and eventual incorporation into photovoltaic device structures.
This Materials World Network project enables collaboration between researchers in the Unites States and Germany that is expected to provide invaluable experience for graduate student and postdoctoral researchers in different cultural and scientific environments, and to help seed future international collaborations and connections between rapidly growing research and commercial activities in solar energy and solid-state nanostructures generally. Germany is a particularly appropriate partner in this regard, in light of its strong commitment to and activity in solar energy technologies. The technological and economic impact of high-efficiency solar energy conversion that could be enabled by the materials advances emerging from this project is potentially dramatic. In addition, the project makes use of facilities and expertise associated with major research centers at each institution ? the California Institute for Telecommunications and Information Technology (CalIT2) at UCSD and the DFG-Center for Functional Nanostructures (CFN) at Karlsruhe. UCSD researchers visiting Karlsruhe benefit from the availability of extensive facilities for materials synthesis and characterization, and from exposure to the broad range of research at CFN on nanostructured materials for electronics, photonics, and biology. Researchers from Karlsruhe visiting UCSD gain exposure to the broad, multidisciplinary research environment that engages issues in basic materials, devices, and systems for telecommunications and information technology, and will benefit from the availability of state-of-the-art experimental materials processing and nanofabrication facilities at CalIT2.
