Background: Reflectance of a ternary epitaxial film @ 658nm

1. Novel Synthesis of Si/Ge-Based Magnetic Semiconductor Films and HeterostructuresFrank Tsui - University of North Carolina - DMR-0441218 Study of Epitaxial Phase Diagram of CoxMnyGe1-x-yComplementary doping using 2 transition metals at optimum ratios can stabilize atomically smooth coherent epitaxial growth at high doping levels. By using the approach, room temperature ferromagnetic p-type semiconductor films have been synthesized. These materials are compatible with Si-based processing, and therefore, promising candidates for the science and technology of spin polarized electronics. Background: Reflectance of a ternary epitaxial film @ 658nm 2D Quasi- 2D 3D x/y ~ 3 2D regime: Atomically smooth,coherent epitaxy with lattice constants obeying Vegard’s law and very low strain (e<<0.1%) High quality p-typemagnetic semiconductors

2. Novel Synthesis of Si/Ge-Based Magnetic Semiconductor Films and HeterostructuresFrank Tsui - University of North Carolina - DMR-0441218 • Collaborations, Education and Outreach • 2 graduate (Liang He and Brian Collins) and 2 REU students (Andrew Fuller from UNC and David Lorang from GA Tech) contributed to the work • Students ran experiments at the Advanced Photon Source (APS) Argonne National Lab. Our work on complementary doping was one of the Science Highlights of 2004 of APS • A. Fuller presented his work to the NC State Legislature last summer in the “Research in the Capital” program, representing undergraduate research in the UNC system • A. Fuller received a Kauffman Fellowship from UNC for his work Magnetic hysteresis loops for Co0.8Mn0.4Ge0.88 epitaxial film: Room temperature ferromagnetic semiconductor T 323K 293K 250K 200K 150K 100K