Scientific Research Division
Der-Hsin Wei (魏德新), Ph. D.
Research Scientist
Nano Science Group
Office: Room S312, R&D Building
E-Mail: dhw@nsrrc.org.tw,
Tel: +886-35780281-7312
Education
1982-1986 B.S. in Physics, National Cheng Kung University
1989-1991 M.S. in Physics, University of Oregon
1991-1996 Ph.D. in Physics, University of Oregon
Employment
1996 – 1997 Postdoctoral Fellow, Institute of Atomic and Molecular Sciences, Academia Sinica
1997 – 2000 Postdoctoral Fellow, Synchrotron Radiation Research Center
1999 – 2000 Visiting Scholar, Experimental System Group, Advanced Light Source
2000 – 2003 Assistant Research Scientist, National Synchrotron Radiation Research Center
2004 – 2013 Associate Research Scientist, National Synchrotron Radiation Research Center
2014 – now Research Scientist, National Synchrotron Radiation Research Center
Research Interest
(1) X-rays Microscopy
The development of microscopy means to visualize the objects that are too small to be seen by human eyes. When the illumination source is X-rays, it is possible to detect objects/events occurred beneath the sample surface (soft X-rays) or buried deep inside bulk (hard X-rays). Depending on the ways to spatially resolved events results from X-rays illumination, approaches including lens or lensless, full field or scanning can be adopted to form two- or three-dimensional X-rays images. For the past years, I have been working on the X-rays PhotoEmission Electron Microscopy (XPEEM) which collects X-rays excited electrons through an electrostatic column. Charge particle simulation was also adopted to study whether the metallic tip commonly adopted in scanning tunneling microscope (STM) can be used to provide X-ray image with resolution similar to that of STM. In future, teamed with Dr. Yao-Jane Hsu and Dr. Chia-Hao Chen, we plan to setup a soft X-ray nanoscopy beamline to host two microscopes; XPEEM and scanning transmission X-ray microscope (STXM), at TPS.
(2) Microscopic insights of interfaces in ferromagnet-organic hybrid structures
The use of organic semiconductors as functional electronic materials is one subject under extensive study. For spintronics, it was thought that the field may go organic by stacking ferromagnetic electrodes with organic semiconductor (OSC) layers. It turns out our knowledge is limited on how spin would inject across ferromagnet(FM)/OSC interface and transport within OSC. Employing multiple experimental techniques such as the magneto-optical Kerr effect (MOKE), near-edge X-rays absorption fine structure (NEXAFS), X-rays photoemission spectroscopy (XPS), and XPEEM to examine several FM-OSC and FM-OSC-FM systems, we worked on both spectroscopic and microscopic evidences to acquire what could happen at FM-OSC interfaces. The confirmation of metal diffusion, as well as the diffusion depth and spin polarization of hybrid orbitals are few good examples.
Selected Publication
1. "Deep Co penetration and spin-polarization of C60 molecules at hybridized Co-C60 interfaces", Pei-Yu Cheng, Meng-Ruei Chiang, Yuet-Loy Chan, Yao-Jane Hsu, Pen-Cheng Wang, and D. H. Wei*, Appl. Phys. Lett. 104, 043303 (2014).
2. "Exploring the magnetic and organic microstructures with photoemission electron microscope", D. H. Wei*, Yuet-Loy Chan, and Yao-Jane Hsu, J. Electron Spectros. Relat. Phenom. 185, 429 (2012).
3. "Direct imaging and spectral identification of the interface in organic semiconductor-ferromagnet heterojunction", D. H. Wei*, Chia-Hao Wang, Hui-Ching Chang, Yuet-Loy Chan, Chih-Hao-Lee, and Yao-Jane Hsu, App. Phys. Lett. 101, 141605 (2012).
4. "Magnetic response of an ultrathin cobalt film in contact with an organic pentacene layer", Yuet-Loy Chan, Ya-Jyuan Hung, Chia-Hao Wang, Ying-Chang Lin, Ching-Yuan Chiu , Yu-Ling Lai, Hsu-Ting Chang, Chih-Hao Lee, Yao-Jane Hsu*, and D. H. Wei*, Phys. Rev. Lett. 104, 177204 (2010).
5. “Collecting photoelectrons with a scanning tunneling microscope nanotip”,Ching-Yuan Chiu, Yuet-Loy Chan, Yao-Jane Hsu and D. H. Wei*, Appl. Phys. Lett. 92, 103101 (2008).
6. “Domain configurations and hysteresis behaviors of ultrathin cobalt film deposited on copper surface”, Yuet-Loy Chan, Jo-Hsuan Sun, Yao-Jane Hsu, and D. H. Wei*, J. of Magn. Magn. Mater. 310, e762 (2007).
7. “Probing the magnetization vectors in layered magnetic structures”, D. H. Wei*, Yao-Jane Hsu, Jo-Hsuan Sun, Chao-Cheng Lin, and Chih-Huang Lai, J. Electron Spectros. Relat. Phenom. 144-147, 737 (2005).
8. “Photoelectron microscopy projects at SRRC”, D. H. Wei*, Yao-Jane Hsu , Ruth Klauser, I. H. Hong, G. C. Yin , and T. J. Chuang, Surf. Rev. Lett. 10(4) , 617 (2003).
9. “Desorption and molecular interactions on surface: CO/Rh(110), CO/Rh(100), and CO/Rh(111)”, D. H. Wei, D. C. Skelton, and S. D. Kevan*, Surf. Sci. 381(1), 49 (1998).