Quantum control of metal/semiconductor hybrid systems: from atomic layer superconductivity to deep sub-diffraction nanolasers
Prof. Chih-Kang Shih,
Department of Physics, The University of Texas at Austin
The ability to control, with atomic precision, heterostructures comprising two dissimilar electronic materials has provided us with an unprecedented opportunity: to tailor novel low-dimensional electronic systems. In this it has been responsible for the discovery of many novel physical phenomena and has facilitated new technologies. While tremendous success has been achieved using semiconductor heterostructures or metallic heterostructures, the same cannot be said for metal/semiconductor heterostructures, due to the fact that most metals do not wet on semiconductors. Over the last decade, however, significant progress has been made in epitaxial growth of metastable metallic thin films on semiconductor substrates. Most interesting is the discovery of an intriguing interplay between the quantum confinement of electronic systems and the surface free energy, leading to the so-called “quantum growth” phenomenon[1, 2]. In the last few years, tremendous research effort has been focused on the exploration of the novel physical properties enabled by the capability to tailor metallic thin films on semiconductor substrates. This talk will focus on two dramatically different applications pursued in our group: (a) atomic layer superconductivity[3-5], and (b) deep sub-diffraction limit plasmonic nanolasers .
1. Smith, A.R., et al., Formation of atomically flat silver films on GaAs with a ''silver mean'' quasi periodicity. Science, 1996. 273(5272): p. 226-228.
2. Zhang, Z.Y., Q. Niu, and C.K. Shih, "Electronic growth" of metallic overlayers on semiconductor substrates. Physical Review Letters, 1998. 80(24): p. 5381-5384.
3. Eom, D., et al., Persistent superconductivity in ultrathin Pb films: A scanning tunneling spectroscopy study. Physical Review Letters, 2006. 96(2).
4. Qin, S.Y., et al., Superconductivity at the Two-Dimensional Limit. Science, 2009. 324(5932): p. 1314-1317.
5. Kim, J., et al., Visualization of geometric influences on proximity effects in heterogeneous superconductor thin films. Nature Physics, 2012. 8(6): p. 463-468.
6. Lu, Y.J., et al., Plasmonic Nanolaser Using Epitaxially Grown Silver Film. Science, 2012. 337(6093): p. 450-453.
Professor Chih-Kang (Ken) Shih received his Ph.D. in Applied Physics at Stanford University in 1988. He joined IBM T.J. Watson Research Center, NY as a postdoc until 1990 when he joined the University of Texas at Austin as a faculty member. Since 2004, he holds the Jane and Roland Blumberg Professor of Physics at UT-Austin. From 2006 to 2013 he directed the UT-IGERT program on "Atomic and Molecular Imaging of Defects and Interfaces in Electronic, Spintronic and Organic/Inorgranic Materials". Professor Shih has made major contributions to quantum size effect on thin film growth and the physical properties of thin film in strong confinement region, as well as nanophotonic properties of semiconductor nanostructures. He is a fellow of the American Physical Society. In 2011, he received the Distinguished Alumni Award, from National Tsing-Hua University, Taiwan, RO.C