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Professor
Gwo,Shangjr(Felix)

 
Personal Website
Office¡G886-3-5742636(PHYS R226)
Laboratory¡G
Nano Sensing & Manipulation Laboratory
Lab Tel¡G886-3-5733238(PHYS R220)
Fax¡G886-3-5723052
E-mail¡Ggwo@phys.nthu.edu.tw

Education
  1. 1987-1993 Ph.D in Physics, The University of Texas at Austin, U.S.A.
  2. 1981-1985 B.E. in Electronic Engineering, National Chiao Tung University, R.O.C.
Professional Experience
Current position¡G
  1. 2002-present, Professor of Physics, National Tsing Hua Univ.,
Experience¡G
  1. 1997-2002, Associate Professor of Physics, National Tsing Hua Univ., R.O.C.
  2. 1996-1997, Research Fellow of Atom Technology Group, National Instiitute for advanted Interdisciplinary Research
  3. 1994-1996, Postdoc of Tokumoto Group, Joint Research Center for Atom Technology
Honors and Awards
  1. Outstanding Research Award, National Science Council (2000)
  2. Outstanding Research Award, National Science Council (2004)
  3. Ten Outstanding Youths in Taiwan (2001¦~)
Research Fields
    1. Scanning Probe Microscopy/Spectroscopy
    2. Nanostructure Physics
    3. Surface Physics
    4. Molecular beam epitaxy of nitride semiconductors
Research Interests and achievement
Updated on September 3, 2006
The research interests in my group are focused on low-dimensional, atomic-scale to nanometer-scale condensed matter systems, mainly based on semiconductor epitaxial materials. Our recent studies include plasma-assisted molecular-beam epitaxy of group-III nitride (InN, GaN, AlN, and their alloys) epitaxial films and nanostructures, optical spectroscopy of light emitting nanomaterials inside optical microcavities, scanning probe microscopy (STM, AFM, EFM, and related novel nanolithographic methods), nanomanipulation and controlled self-assembly of low-dimensional nanomaterials, and scanning tunneling and synchrotron-radiation photoelectron spectroscopies of III-nitride surface and interface electronic structures.

Some highlighted research topics are listed as follows:
  • Epitaxial studies of commensurately matched indium nitride (InN), gallium nitride (GaN), aluminum nitride (AlN) epitaxial systems, including heterojunctions, quantum wells, quantum dots, self-aligned nanorods, and quantum disks in nanorods
    By using plasma-assisted molecular-beam epitaxy, we have recently demonstrated that high-quality III-nitride heterojunctions can be realized via the concept of commensurate lattice match. In particular, we showed that atomically abrupt InN/AlN heterojunction can be formed despite of a tremendous mismatch in lattice constants (>10%). This finding can open up new pathways for III-nitride-related fundamental studies and device applications. In addition, we have developed epitaxial growth techniques for forming III-nitride quantum dots, self-aligned nanorods, and quantum disks in nanorods. These nanomaterials would be very useful for future device applications in the fields of light-emitting devices, solar cells, and high-speed transistors.
  • Optical spectroscopy
    We are using the techniques of spatially- and time-resolved photoluminescence spectroscopy for studying the interactions of light-emitting nanomaterials within optical microcavities (such as III-nitride nanorods or whispering-gallery-mode silica microspheres/rings). We are interested in both weak- and strong-coupling regimes. Theses studies can lead to novel light-emitting devices and can be used develop the necessary means for quantum manipulation of matter states, which is important in solid-state quantum information processing.
  • Electronic structures of III-nitride surfaces and interfaces
    Band structure line-ups of III-nitride heterojunctions are important electronic properties to realize both electronic and photonic device applications. Also, surface and interface electronic structures of III-nitride are crucial for understanding the characteristics of III-nitride materials (especially for InN, a focused material for recent III-nitride research activities). For these largely unexplored research areas, we will utilize the techniques of scanning tunneling microscopy/spectroscopy and synchrotron-radiation photoelectron spectroscopy for a comprehensive understanding of related electronic properties.
  • Nanofabrication
    Using various scanning probe lithography and pattern transfer techniques, we have succeeded in developing new methods for fabricating nanostructures which can be used in micooptics and optoelectronics as well as devices based on artificial photonic/plasmonic bandgap structures. Recently, we have also built a specialized scanning electron microscope (SEM) system, which allows in-situ manipulation, assembly, and measurement of individual one-dimensional nanomaterials via a four-probe nanomanipulator. At present, we are working on nanosensing and nanophotonic applications based on these assembled one-dimensional nanomaterials.
  • Soft condensed matter systems Colloidal nanoparticles are important building blocks for the emerging applications in nanosensing and nanophotonics. We have developed and are continually working on novel approaches for multiple-length-scale (nm to mm) controlled self-assembly of functionalized colloidal nanoparticles onto patterned molecular layers or electrostatic charge patterns.

    • Selected Publications
    1. [2006] C.-F. Chen, S.-D. Tzeng, M.-H. Lin, and S. Gwo,* ¡§Electrostatic assembly of gold colloidal nanoparticles on organosilane monolayers patterned by microcontact electrochemical conversion,¡¨ Langmuir 22, 7819 (2006).
    2. [2006] C.-H. Shen, H.-Y. Chen, H.-W. Lin, S. Gwo,* A. A. Klochikhin, and V. Yu. Davydov, ¡§Near-infrared photoluminescence from vertical InN nanorod arrays grown on silicon: Effects of surface electron accumulation layer,¡¨ Appl. Phys. Lett. 88, 253104 (2006).
    3. [2006] S.-D Tzeng, K.-J. Lin, J.-C. Hu, L.-J. Chen, and S. Gwo,* ¡§Templated self-assembly of colloidal nanoparticles controlled by electrostatic nanopatterning on Si3N4/SiO2/Si electret,¡¨ Adv. Mater. 18, 1147 (2006)
    4. [2006] C.-L. Wu, C.-H. Shen, and S. Gwo,* ¡§Valence band offset of wurtzite InN/AlN commensurate heterojunction determined by photoelectron spectroscopy,¡¨ Appl. Phys. Lett. 88, 032105 (2006).
    5. [2005] C.-L. Wu, C.-H. Shen, H.-W. Lee, H.-M. Lee, and S. Gwo,* ¡§Direct evidence of 8:9 commensurate heterojunction formed between InN and AlN on c-plane,¡¨ Appl. Phys. Lett. 87, 241916 (2005).
    6. [2005]Ahn,* C.-H. Shen, C.-L. Wu, and S. Gwo, ¡§Spectroscopic ellipsometry study of wurtzite InN epitaxial films on Si(111) with varying carrier concentrations,¡¨ Appl. Phys. Lett. 86, 201905 (2005).
    7. [2005] C.-F. Chen, S.-D Tzeng, H.-Y. Chen, and S. Gwo,* ¡§Silicon microlens structures fabricated by scanning-probe gray-scale oxidation,¡¨ Optics Lett. 30, 652 (2005).
    8. [2004] C.-L. Wu, L-J. Chou, and S. Gwo,* ¡§Size- and shape-controlled GaN nanocrystals grown on Si(111) substrate by reactive epitaxy,¡¨ Appl. Phys. Lett. 85, 2071 (2004).
    9. [2004] S. Gwo,* C.-L. Wu, C.-H. Shen, W.-H. Chang, T. M. Hsu, J.-S. Wang, and J.-T. Hsu, ¡§Heteroepitaxial growth of wurtzite InN films on Si(111) exhibiting strong near-infrared photoluminescence at room temperature,¡¨ Appl. Phys. Lett. 84, 3765 (2004)
    10. [2003] S. Gwo,* C.-P. Chou, C.-L. Wu, Y.-J. Yeh, S.-J. Tsai, W.-C. Lin, and M.-T. Lin, ¡§Self-limiting size distribution of supported cobalt nanoclusters at room temperature,¡¨ Phys. Rev. Lett. 90, 185506 (2003).
    11. [2002] S.-D. Tzeng, C.-L. Wu, Y.-C. You, T. T. Chen, S. Gwo,* and H. Tokumoto, ¡§Charge imaging and manipulation using carbon nanotube probes,¡¨ Appl. Phys. Lett. 81, 5042 (2002).
    12. [2001]H. Ahn, C.-L. Wu, S. Gwo, C. M. Wei, and Y. C. Chou,* ¡§Structure determination of the Si3N4/Si(111)-(8„e8) surface: A combined study of Kikuchi electron holography, scanning tunneling microscopy, and ab initio calculations,¡¨ Phys. Rev. Lett. 86, 2818 (2001).
      • All Publications (Expansible)

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