Research Interests:

Our group is involved in research on self-assembled nanostructures using molecular beam epitaxy. We work on self-assembled quantum wires and quantum dots in III-V compounds semiconductors. Students and postdoctoral researchers are using both epitaxial growth and spectroscopy techniques to understand the physical properties associated with two or three dimensional carrier confinement in these nano structures. The work on self-assembled quantum dots is also focused on developing novel devices, which use the unique physical properties of the quantum dots. The "atom like" properties of quantum dots make them a potential candidate for quantum gates to be used in quantum computing. Spin injection in quantum dots using hybrid magnetic-semiconductor structures is becoming a major topic of research in the group.

Among the topics under investigation are: Growth and spectroscopy of self assembled quantum dots and quantum dot lattices Spectroscopy of tunable quantum dot molecules Quantum dot optical memory in the GaN system Quantum dot infrared detectors

Hybrid magnetic-semiconductor structures have become a major topic of research in the group. Molecular beam epitaxy of the Fe-GaAs-InAs system and the GaMnAs-GaAs -InAs system has been developed with a focus on novel spintronic device applications. A quantum dot spin LED which shows polarized spin injection through its magnetically dependent electroluminescence has been developed. The physics of spin injection in quantum dots is under investigation using this device.

Finally a new effort on developing the grapho-epitaxy of conducting and magnetic polymers has been started in our group with the collaboration of professor E.Kramer of the polymer group. Here we use the ultra small (nanosize) patterning of a surface to force the molecular crystals to all grow with the same orientation.

Selected Publications:

• G.Medeiros-Ribeiro, F.G.Pikus, P.M.Petroff, A.L.Efros. "Single electron charging and Coulomb interactions in InAs self assembled quantum dot arrays", Phys. Rev. B 55(3), 1568 (1997).
• Wellmann, P.J., Garcia, J.M.; Feng, J.-L., Petroff, P.M. "Giant magnetoresistance in a low-temperature GaAs/MnAs nanoscale ferromagnet hybrid structure", Applied Physics Letters 73(22), 329 (1998).
• K.H.Schmidt, G.Medeiros Ribeiro, P.M.Petroff, "Photoluminescence of charged InAs self assembled quantum dots" Phys. Rev B 7(58), 3597 (1998).
• T. Lundstrom, W. Schoenfeld, H. Lee, P.M. Petroff, "Exciton strorage in Semiconductor Self-Assembled Quantum Dots." Science 286, 2312-2314 (1999).
• P.P. Paskov, P.O. Holtz, B. Monemar, J.M. Garcia, W.V. Schoenfeld, P.M. Petroff "Photoluminescence up-conversion in InAs/GaAs self-assembled quantum dots" Applied Physics Letters 77(6), 812 (2000).
• Schoenfeld, W.V., Metzner, C.; Letts, E., Petroff, P.M., "Spectroscopy of strain-induced quantum dots in GaAs/Al/sub x/Ga/sub 1-x/As quantum well structures", Physical Review B 63(20), 205319 (2001).
• H. Lee, J.A. Johnson, M.Y. He, J.S. Speck, P.M. Petroff, "Strain engineered self-assembled semiconductor quantum dot lattices", Applied Physics Letters 78(1),105 (2001).
• P.M.Petroff, A/Lorke, A.Imamoglu, "Epitaxial self Assembled Quantum Dots", Physics Today 46 ( 2001).