Material Science Group

Transient setup and GaN:Co surface

People

Research Activities

1. Thin films and multilayer structures of advanced functional materials, such as high T_c superconductors, ABO₃ compounds, and various perovskite transition metal oxides. Techniques include various high vacuum deposition systems (e.g., magnetron sputtering, e-beam evaporation, laser beam epitaxial, and pulse laser ablation), low temperature and B high field measurement facility, x-ray diffraction, scanning probe microscopy, and clean room.
2. Ultrathin films and heterostructures of semiconductors and topological insulators grown by molecular-beam epitaxy. Studies of surface growth kinetics and surface structural and electronic properties by scanning probing microscopy, electron diffraction and holography, photoemission electron spectroscopy and Auger electron spectroscopy, etc.
3. Properties and effects of defects on transport and optical behavior of semiconductors, such as GaN and ZnO. Techniques include positron annihilation spectroscopy, deep level transient spectroscopy, temperature dependent Hall, IV and CV measurements, and luminescence spectroscopy.
4. Fabrication and characterization of organic, organic/inorganic nanocomposite, inorganic optoelectronic devices (LEDs and solar cells), as well as fabrication and characterization of various nanostructures (mostly metal oxides and/or wide band gap semiconductors). The available facilities include fume cupboards, tube furnaces, spin-coater, thermal evaporators, and E-beam/sputtering deposition systems, UV/Vis/NIR spectrometers, photocatalytic dye degradation, and setups for power conversion efficiency and external quantum efficiency measurements for solar cells.  

Some Representative Publications

Dr. A.B. Djurišić

1. M. Guo, M. C. A. Ng, F. Z. Liu, A. B. Djurišić, W. K. Chan, H. M. Su and K. S. Wong, “Effect of Native Defects on Photocatalytic Properties of ZnO”, J. Phys. Chem. C 115, 11095-11101, 2011.
2. A. Ng, C. H. Li, M. K. Fung, A. B. Djurišić, W. K. Chan, J. A. Zapien, K. Y. Cheung, W.-Y. Wong, “Accurate determination of the index of refraction of polymer blend films by spectroscopic ellipsometry”, J. Phys. Chem. C 114, 15094-15101, 2010.
3. A. B. Djurišić, A. M. C. Ng, X. Y. Chen, “ZnO nanostructures for optoelectronics: material properties and device applications”, Prog. Quantum Electron. 34, 191-259, 2010.
4. X. Z. Wang, W.-Y. Wong, L. Yan, K.-Y. Cheung, A. Ng, A. B. Djurišić, W. K. Chan, “Very Low-Bandgap Metallopolyynes of Platinum with Cyclopentadithiophenone Ring for Organic Solar Cells Absorbing Down to the Near-infrared Spectral Region“, Macromolecular Rapid Communications 31, 861-867, 2010.
5. A. M. C. Ng, Y. Y. Xi, Y. F. Hsu, A. B. Djurišić, W. K. Chan, S. Gwo, H. L. Tam, K. W. Cheah, P. W. K. Fong, H. F. Lui, C. Surya, “GaN/ZnO nanorod light emitting diodes with different emission spectra”, Nanotechnology 20, 445201 (1-8), 2009.
6. Y. Y. Xi, A. M. C. Ng, Y. F. Hsu, A. B. Djurišić, B. Q. Huang, L. Ge, X. Y. Chen, W. K. Chan, H. L. Tam, K. W. Cheah, “Effect of annealing on the performance ot CrO3/ZnO light emitting diodes”, Appl. Phys. Lett. 94, 203502 (1-3), 2009.
7. Y. C. Zhong, A. B. Djurišić, Y. F. Hsu, K. S. Wong, G. Brauer, C. C. Ling, W. K. Chan, ”Exceptionally long exciton photoluminescence lifetime in ZnO tetrapods”, J. Phys. Chem. C 112(42); 16286-16295, 2008.
8. L. Liu, C. L. Ho, W.-Y. Wong, K.-Y. Cheung, M. K. Fung, W. T. Lam, A. B. Djurišić, W. K. Chan, "Effect of Oligothienyl Chain Length on Tuning the Solar Cell Performance in Fluorene-Based Polyplatinynes”, Adv. Funct. Mater.18, 2824-2833, 2008.
9. Y. F. Hsu, Y. Y. Xi, A. B. Djurišić, W. K. Chan, “ZnO nanorods for solar cells: hydrothermal growth vs. vapor deposition”, Appl. Phys. Lett. 92, 133507 (1-3), 2008.
10. Y. Y. Xi, Y. F. Hsu, A. B. Djurišić, A. M. C. Ng, W. K. Chan, H. L. Tam, K. W. Cheah, “NiO/ZnO light emitting diodes by solution based growth”, Appl. Phys. Lett. 92, 113505 (1-3), 2008.
11. Y. F. Hsu, Y. Y. Xi, K. H. Tam, A. B. Djurišić, J. Luo, C. C. Ling, C. K. Cheung, A. M. C. Ng, W. K. Chan, X. Deng, C. D. Beling, S. Fung, K. W. Cheah, P. W. K. Fong, C. Surya, ”Undoped p-type ZnO nanorods by hydrothermal method”, Adv. Funct. Mater. 18, 1020-1030, 2008.
12. A. M. C. Ng, A. B. Djurišić, K. H. Tam, W. M. Kwok, W. K. Chan, D. L. Phillips, and K. W. Cheah 'Organic nanoclusters on inorganic nanostructures for tailoring emission properties of organic materials', Adv. Funct. Mater. 18, 566-574, 2008.
13. W.-Y. Wong, X.-Z. Wang, Z. He, A. B. Djurišić, K. Y. Cheung, Y. C. Tung, A. M. C. Ng, Y. Y. Xi, C. S. K. Mak, W. K. Chan, “Tuning the Functional Properties and Solar Cell Efficiency with the Number of Thienyl Rings in Highly Conjugated Platinum-containing Poly(aryleneethynylene)s”, J. Am. Chem. Soc. 129, 14372-14380, 2007.
14. W. Y. Wong, Z. He, A. B. Djurišić, C. T. Yip, K. Y. Cheung, H. Wang, C. S. K. Mak, W. K. Chan, "Metallated conjugated polymers as a new avenue towards high-efficiency polymer solar cells”, Nature Mater. 6(7), 521-527, (2007).
15. A. B. Djurišić, Y. H. Leung, K.H. Tam, Y. F. Hsu, L. Ding, W. K. Ge, Y. C. Zhong, K. S. Wong, W. K. Chan, H. L. Tam, K. W. Cheah, W. M. Kwok, D. L. Phillips, “Defect emissions in ZnO nanostructures”, Nanotechnology 18, 095702 (1-8), 2007.
16. K. Y. Cheung, C. T. Yip, A. B. Djurišić, Y. H. Leung, W. K. Chan, “Long K-doped titania and titanate nanowires on Ti foil and FTO/quartz substrates for solar cell applications”, Adv. Funct. Mater. 17, 555-562, 2007.

For details, please refer to the Homepage of Optoelectronics and Nanomaterials Lab.

Prof. J. Gao

1. "Current-induced Metastable Resistive State in Epitaxial Thin Films of La_1-xCa_xMnO₃ (x=0.2,0.3)", J. Gao and F.X. Hu, Applied Physics Letters, 86, 092504 (2005) 
2. "Abnormal Reduction of Eu Ions and Luminescence in CaB₂O₄: Eu Thin Films", J.H. Hao and J. Gao, Applied Physics Letters, 85 (17), 3720-3722 (2004) 
3. "Unusual Current-induced Electroresistance in Epitaxial Thin Films of La_0.8Ca_0.2MnO₃", F.X. Hu and J. Gao, Physical Review B, 69 (21), 212413 (2004) 
4. "Current-induced Effect on the Resistivity of Epitaxial Thin Films of La_0.7Ca_0.3MnO₃ and La_0.85Ba_0.15MnO₃", J. Gao, S.Q. Shen, T.K. Li and J.R. Sun, Applied Physics Letters, 82 (26), 4732-4734 (2003) 
5. "Electronic States of the La_0.9Sn_0.1MnO₃ Epitaxial Thin Films", J. Gao, S.Y. Dai and T.K. Li, Physical Review B, 67 (15), 153403 (2003) 
6. "High-T_c Superconducting Josephson Junctions with a Continually Graded Barrier", J. Gao, J.L. Sun, S.M. So, W.H. Tang and T.K. Li, Applied Physics Letters, 79 (19), 3101-3103 (2001)  

Dr. F.C.C. Ling

1. "Deep Level Defects in a Nitrogen-implanted ZnO Homogeneous p-n Junction", Q.L. Gu, C.C. Ling, G. Brauer, W. Anwand, W. Skorupa, Y.F. Hsu, A.B. Djurisic, C.Y. Zhu, S. Fung and L.W. Lu, Appl. Phys. Lett., 92, 222109 (2008).
2. "Hydrogen Peroxide Treatment Induced Rectifying Behavior of Au/n-ZnO Contact", Q.L. Gu, C.C. Ling, X.D. Chen, C.K. Cheng, A.M.C. Ng, C.D. Beling, S. Fung, A.B. Djurisic, L.W. Lu, G. Brauer and H.C. Ong, Appl. Phys. Lett., 90, 122101 (2007). Selected for: Virtual Journal of Nanoscale Science & Technology, 15, issue 13.
3. "Low energy electron irradiation induced deep level defects in 6H-SiC: The implication for the microstructure of the deep levels E₁/E₂", X.D. Chen, C.L. Yang, M. Gong, W.K. Ge, S. Fung, C.D. Beling, J.N. Wang, M.K. Lui and C.C. Ling, Physical Review Letters, 92 (12), 125504 (2004).
4. "Gallium vacancy and the residual acceptor in undoped GaSb studied by positron lifetime spectroscopy and photoluminescence", C.C. Ling, W.K. Mui, C.H. Lam, C.D. Beling, S. Fung, M.K. Lui, K.W. Cheah, K.F. Li, Y.W. Zhao and M. Gong, Applied Physics Letters, 80 (21), 3934-3936 (2002).
5. "EL2 donor state in semi-insulating GaAs revealed by frequency dependent positron mobility measurement", H.L. Au, C.C. Ling, P.K. Panda, T.C. Lee, C.D. Beling and S. Fung, Physical Review Letters, 73 (20), 2732-2735 (1994).

For details, please refer to the Homepage of Material Physics Laboratory.

Dr. H.S. Wu

1. "Direct Observation of Ga Adlayer on GaN (0001) Surface by LEED Patterson Inversion", S.H. Xu, H.S. Wu, X.Q. Dai, W.P. Lau, L.X. Zheng, M.H. Xie and S.Y. Tong, Physical Review B, 67 (12), 125409 (2003).
2. "Surface Atomic Arrangement Visualization via Reference-Atom-Specific Holography", H.S. Wu, S.H. Xu, K.M.S. Ma, W.P. Lau, M.H. Xie and S.Y. Tong, Physical Review Letters, 89 (21), 216101 (2002).
3. "Surface Patterson Function by Inversion of Low-Energy Electron Diffraction I-V Spectra at Multiple Incident Angles", H.S. Wu and S. Y. Tong, Physical Review Letters, 87 (3), 36101 (2001).
4. "Convergent N²-scalling Iterative Method of Photoelectron Diffraction and Low-energy Electron Diffraction for Ordered or Disordered Systems", H.S. Wu and S.Y. Tong, Physical Review B, 59 (1), 1-4 (1999).
5. "New Experimental Technique for Determining Real_Space Atomic Image Applied to Aluminum Adsorbed on Silicon(111)", H.S. Wu, G.J. Lapeyre, H. Hong and S.Y. Tong, Physical Review Letters, 71, 2, 251-254 (1993).

Prof. M.H. Xie

1. "Superlattices of Bi₂Se₃/In₂Se₃: Growth Characteristics and Structural Properties", Z.Y. Wang, X. Guo, H.D. Li, T.L. Wong, N. Wang and M.H. Xie, Appl. Phys. Lett., 99, 023112 (2011).
2. "The Van Der Waals Epitaxy of Bi₂Se₃ on the Vicinal Si(111) Surface: An Approach for Preparing High-quality Thin Films of a Topological Insulator", H.D. Li, Z.Y. Wang, X. Kan, X. Guo, H.T. He, Z. Wang, J.N. Wang, T.L. Wong, N. Wang and M.H. Xie, New J. Phys., 12, 103038 (2011).
3. "Reactive interface formation and Co-induced (√7×√7) superstructure on a GaN(0001) pseudo-(1×1) substrate surface”, Phys. Rev. B 81, 233302 (2010)
4. "Dislocation network at InN/GaN interface revealed by scanning tunneling microscopy”, Y. Liu, Y. Cai, L.X. Zhang, M.H. Xie, N. Wang, S.B. Zhang, and H.S. Wu, Appl. Phys. Lett. 92, 230917 (2008)
5. "A study of Al_1-xIn_xN growth by reflection high-energy electron diffraction-incorporation of cation atoms during molecular-beam epitaxy”, B.M. Shi, Y. Wang, M.H. Xie, H.S. Wu, Appl. Phys. Lett. 92, 101902 (2008)
6. "Kinetic energy barriers on the GaN(0001) surface: A nucleation study by scanning tunneling microscopy”, H. Zheng, M.H. Xie, H.S. Wu, Q.K. Xue, Phys. Rev. B 77, 045303 (2008)
7. "Wetting of GaN islands by excess Ga: Origin of different appearances of GaN islands in scanning tunneling microscopy”, H. Zheng, M.H. Xie, H.S. Wu, and Q.K. Xue, Phys. Rev. B 75, 205310 (2007)
8. "InN island shape and its dependence on growth condition of molecular-beam epitaxy”, Y.G. Cao et al., Appl. Phys. Lett. 83, 5157 (2003)
9. "Growth mode and strain evolution during InN growth on GaN(0001) bymolecular-beam epitaxy”, Y.F. Ng et al., Appl. Phys. Lett. 81, 3960 (2002)
10. "Observation of ‘Ghost’ Islands and Surfactant Effect of Surface Gallium Atomsduring GaN Growth by Molecular Beam Epitaxy”, L.X. Zheng et al., Phys. Rev. Lett.85, 2352 (2000)
11. "Reduction of Threading Defects in GaN Grown on Vicinal SiC(0001) byMolecular Beam Epitaxy”, M.H. Xie et al., Appl. Phys. Lett. 77, 1105 (2000)
12. "Anisotropic Step-Flow Growth and Island Growth of GaN(0001) by Molecular Beam Epitaxy”, M.H. Xie, S. M. Seutter, W.K. Zhu, L.X. Zheng, H.S. Wu and S.Y. Tong, Phys. Rev. Lett. 82, 2749-2752 (1999)