Scientific Research Division

Tun-Wen Pi (皮敦文), Ph. D.

Research Scientist

Nano Science Group

Office: Room S309, R&D Building

E-Mail: pi@nsrrc.org.tw, 

Tel: +886-35780281-7309

 

Education               

1983－1990  Ph.D. in Department of Physics, Iowa State University, Ames, Iowa, USA

                           

Employment

1992－now  National Synchrotron Radiation Research Center

 

Research Interest

    Metal-oxide-semiconductor field effect transistors (MOSFETs) using high-k dielectrics/metal gates on high carrier mobility channels are called for post Si complementary MOS (CMOS) applications to offer excellent device performance with low power consumption. The consensus among academic research and industrial development is adopting InGaAs as the n-channel material, due to their high electron mobility. A high-quality oxide/InGaAs interface is the key for realizing high performance InGaAs MOSFETs. Thus, research efforts in probing and analyzing this interface electrically, chemically, and electronically have been feverish. Prior to the oxide deposition, such as a precursor purge in atomic layer deposition (ALD), the (In)GaAs surface must be free from impurity, such as oxygen, and/or remains stoichiometric; only under this condition, would meaningful physics of interfacial electronic structure be revealed.
    In my laboratory, then, we employ high-resolution core-level photoemission to study the electronic structure of high-k dielectrics on atomically clean III-V surfaces. The clean III-V surfaces must be well understood before one marches into the realm of high-k interfaces. The prototypical surfaces are GaAs(001)-4x6, GaAs(001)-2x4, GaAs(111)A-2x2, and InxGayAs(001)-4x2. They are probed with synchrotron radiation photoemission under the as-grown condition in a molecular-beam-epitaxy (MBE) chamber without air exposure. High k dielectrics are prepared by MBE as well as by atomic-layer deposition (ALD). Materials cover from rare-earth oxides and Al2O3. The electronic structure of high-k interfaces thus obtained are correlated with the electric characteristics.

 

 

 

 

 

 

 

 

 

 

Selected Publication

 

1. T. W. Pi*, Y. H. Lin, Y. T. Fanchiang, T. H. Chiang, C. H. Wei, Y. C. Lin, G. K. Wertheim, J. Kwo*, and M. Hong*, In-situ atomic layer deposition of tri-methylaluminum and water on pristine single-crystal (In)GaAs surfaces: electronic and electric structures, Nanotechnology 26, 164001 (2015). DOI:10.1088/0957-4484/26/16/164001

 

2. W. H. Chang, T. D. Lin, M. H. Liao*, T. W. Pi*, J. Kwo*, and M. Hong*, High /InGaAs for ultimate CMOS – interfacial passivation, low ohmic contacts, and device performance (Invited), ECS Transaction 61, 113-124 (2014). DOI:10.1149/06120.0113ecst

 

3. T. W. Pi*, T. D. Lin, W. H. Chang, Y. C. Chang, J. Kwo*, and M. Hong*, Semiconductor-insulator interfaces– High  dielectrics on (In)GaAs, Encyclopedia EEE (25 April, 2014). DOI: 10.1002/047134608X

 

4. T. W. Pi*, T. D. Lin, H. Y. Lin, Y. C. Chang, G. K. Wertheim*, J. Kwo*, and M. Hong*, Synchrotron radiation photoemission study of interfacial electronic structure of HfO2 on In0.53Ga0.47As(001)-4x2 from atomic layer deposition, Appl. Phys. Lett. 104, 042904 (2014). DOI: 10.1063/1.4863440

 

5. T. W. Pi*, H. Y. Lin, T. H. Chiang, Y. T. Liu, Y. C. Chang, T. D. Lin, G. K. Wertheim*, J. Kwo*, and M. Hong*, Surface atoms core-level shifts in single crystal GaAs surfaces: Interactions with trimethylaluminum and water prepared by atomic layer deposition, Appl. Surf. Sci. 284, 601-610 (2013). DOI:j.apsusc.2013.07.140

 

6. T. W. Pi*, H. Y. Lin, T. H. Chiang, Y. T. Liu, G. K. Wertheim, J. Kwo*, and M. Hong*, Interfacial electronic structure of trimethyl-aluminum and water on an In0.20Ga0.80As(001)-4x2 surface: A high-resolution core-level photoemission study, J. Appl. Phys. 113, 203703 (2013).  DOI:10.1063/1.4807400

 

7. Tun-Wen Pi*, Hsiao-Yu Lin, Ya-Ting, Liu, Tsung-Da Lin, Gunther K. Wertheim*, Jueinai Kwo*, and Minghwei Hong*, Atom-to-atom interactions for atomic layer deposition of trimethylaluminum on Ga-rich GaAs(001)-4x6 and As-rich GaAs(001)-2x4 surfaces: A synchrotron-radiation photoemission study, NanoResearch Letters, 8, 169 (2013). 

DOI:10.1186/1556-276X-8-169

 

8. M. L. Huang, Y. H. Chang, P. Chang, J. Y. Shen, B. R. Chen, G. K. Wertheim, T. W. Pi*, M. Hong*, and J. Kwo*, Growth mechanism of atomic layer deposited Al2O3 on GaAs(001)-4x6 surface with trimethylaluminum and water as precursors, Appl. Phys. Lett. 101, 212101 (2012). DOI:10.1063/1.4767129

 

9. T. W. Pi*, B. R. Chen, M. L. Huang, T. H. Chiang, G. K. Wertheim, M. Hong, and J. Kwo, Surface-atom core-level shift in GaAs(111)A-2x2, J. Phys. Soc. Jpn. 81, 064603 (2012). DOI:10.1143/JPSJ.81.064603

 

10. T. W. Pi, M. L. Huang, W.C. Lee, L. K. Chu, T. D. Lin, T. H. Chiang, Y. C. Wang, M. Hong, and J. Kwo, High-resolution core-level photoemission study of CF4-treated Ga2O3(Gd2O3) gate dielectric on Ge probed by synchrotron radiation, Appl. Phys. Lett. 98, 062903 (2011).DOI:10.1063/1.3551726