Researcher Portfolio

Wei Jun (Dr)
Principal Scientist I
Large Area Processing
Introduction:

Dr Wei's work experiences include Associate Professor and Head of Materials Research Group at Tsinghua University; Visiting Professor at Ecole Centrale de Lyon, France. His R&D activities include micro/nanojoining, carbon nanotubes, nanostructuring, nanocomposites, advanced interconnection, microsystems and nanosystems fabrication and packaging, hermetic/vacuum sealing, low temperature wafer/substrate bonding, as well as clean energy. He is also the Guest and Adjunct Professor at several international and local universities.

Dr. Wei is a member of the American Society of Mechanical Engineers. He is serving several international conference and professional committees. He has published more than 200 technical papers and holds more than 30 patents and technology disclosures.

Research Interest:• Carbon nanotubes growth, devices and interconnection
• Nanostructuring 
• Nanocomposites 
• Micro/nanojoining 
• High density interconnection 
• Low temperature metal, wafer/substrate bonding 
• Microsystems and nanosystems fabrication and packaging 
• Clean energy
BioNotes:1991: PhD, Materials Science and Engineering, Tsinghua University, China.
Publications:

Journal

1. C. W. Lee, F. M. Chen, J. Wei, X. D. Han,  Y. Chen, M. B. Chan-Park and L. J. Li, “Solution Processable Carbon Nanotubes for Semiconducting Thin Film Transistor Devices”, Advanced Materials, vol 22 Issue 11, pp. 1278 – 1282 (2010).   
2. J. N. Tey, S. Gandhi, I. P. M. Wijaya, Al. Palaniappan, J. Wei, I. Rodriguez, C. R. Suri and S. G. Mhaisalkar, “Direct Detection of Heroin Metabolites using a Carbon Nanotubes Liquid Gated Field Effect Transistor based Competitive Immunoassay”, Small, vol 6 Issue 9, pp. 993 – 998 (2010).  
3. J. N. Tey, I. P. M. Wijaya J. Wei,  I. Rodriguez, S. G. Mhaisalkar, “Microfluidic-integrated Nanotube and Nanowire Field Effect Transistors based Biosensors”, Microfluidics and Nanofluidics, 2010 (invited review paper, accepted) 
4. Naing Naing Aun, Wei Zhou, Chwee Sim Goh, Sharon Mui Ling Nai and Jun Wei, “Effect of Carbon Nanotubes on Corrosionof Mg-CNT Composites”, Corrosion Science, vol 52, Issue 5, pp. 1551–1553 (2010).
5. X. Y. Ye, M. F. Chen, M. Yang, J. Wei and D. B. Liu, “In vitro Corrosion Behaviour and Cytocompatibility of Mg-Zn-Zr Alloy and its Composite Reinforced with Nano-Hydroxyapatite”, Journal of Materials Science: Materials in Medicine, vol 21, Number 4, pp. 1321-1328 (2010).
6. H. Xu, C. Q. Liu, V. V. Silberschmidt, Z. Chen, J. Wei, “Initial Bond Formation in Thermosonic Gold Ball Bonding on Aluminium Metallization Pads”, Journal of Materials Processing Technology, vol 210, Issue 8, pp. 1035-1042 (2010).
7. Y. D. Han, H. Y. Jing, S. M. L. Nai, L. Y. Xu, C. M. Tan and J. Wei, “Temperature Dependence of Creep and Hardness of Sn-Ag-Cu Lead-free Solder”, Journal of Electronic Materials, vol. 39, Number 2, pp. 223-229 (2010).
8. H. Xu, C. Q. Liu, V. V. Silberschmidt, Z. Chen, J. Wei, “The Role of Bonding Duration in Wire Bond Formation: A Study of Footprints of Thermosonic Gold Wire on Aluminium Pad”, Microelectronics International, vol 27(1), pp. 11-16 (2010).
9. S. M. L. Nai, J. Wei and M. Gupta, “Interfacial Intermetallic Growth and Shear Strength of Lead-Free Composite Solder Joints”, Journal of Alloys and Compounds, vol 473, Issues 1-2, pp. 100–106 (2009).
10. J. W. Zheng, S. M. L. Nai, M. F. Ng, P. Wu, J. Wei and M. Gupta, “DFT Study on Nano Structures of Sn/CNT Complex for Potential Li-ion Battery Application”, Journal of Physical Chemistry C, vol 113, No. 31 , pp. 14015 – 14019 (2009).
11. Y. D. Han, H. Y. Jing, S. M. L. Nai, C. M. Tan, J. Wei, L. Y. Xu and S. R. Zhang, “A Modified Constitutive Model for Creep of Sn-3.5Ag-0.7Cu Solder Joints”, Journal of Physics D: Applied Physics, vol 42, Number 12, 125411 (2009).
12. Y. D. Han, H. Y. Jing, S. M. L. Nai, L. Y. Xu, C. M. Tan and J. Wei, “Indentation Size Effect on the Creep Behavior of a SnAgCu Solder”, International Journal of Modern Physics B, vol 24, Issue: 1, pp. 267-275 (2010).
13. K. P. Yung, J. Wei, B. K. Tay, “Formation and Assembly of Carbon Nanotube Bumps for Interconnection Applications”, Diamond and Related Materials, vol 18, Issue 9, pp. 1109-1113 (2009).
14. J. Li, Q. H. Foo, X. F. Ang, J. Wei and C. C. Wong, “Chain Length Dependence of SAMs-assisted Copper Thermocompression Bonding”, Advanced Materials Research, vol 74, pp. 291-294 (2009).
15. X. F. Ang, J. Wei, Z. Chen and C. C. Wong, “Enabling Low Temperature Copper Bonding With an Organic Monolayer”, Advanced Materials Research, vol 74, pp. 133-136 (2009).
16. X. F. Ang, J. Wei, Z. Chen and C. C. Wong, “Ambient Copper-Copper Thermocompression Bonding using Self-Assembled Monolayers”, Materials and Technologies for 3-D Integration, Book Series: Materials Research Society Symposium Proceedings, vol: 1112, pp.91-99 (2009).
17. C. W. Lee, X. C. Dong, S. H. Goh, J. L. Wang, J. Wei and L. J. Li, “Illumination-Enhanced Hysteresis of Transistors Based on Carbon Nanotube Networks”, Journal of Physical Chemistry C, vol 113 (12), pp. 4745–4747 (2009).  
18. G. S. Zhang, H. Y. Jing, L. Y. Xu, J. Wei and Y. D. Han, “Creep Behavior of Eutectic 80Au/20Sn Solder Alloy”, Journal of Alloys and Compounds, vol 476, Issues 1-2, pp. 138-141 (2009). 
19. Q. Liu, Z. F. Liu, X. Y. Zhang, L. Y. Yang, N. Zhang, G. L. Pan, S. G. Yin, Y. S. Chen and J. Wei, “Polymer Photovoltaic Cells Based on Solution-Processable Graphene and P3HT”, Advanced Functional Materials, vol 19(6), pp. 894-904 (2009).
20. Z. Q. Wang,  J. C. Deng, X. M. Wu, N. Jing, Z. Y. Hu, X. M. Cheng, Y. L. Hua, J. Wei, and S. G. Yin, “The Influence of PEDOT:PSS Buffer Layer on The Performance of Organic Photocoupler”, Optoelectronics Letters, vol 5(3), pp. 0173-0176 (2009).
21. Z. Q. Wang, J. C. Deng, X. M. Wu, N. Jing, Z. Y. Hu, X. M. Cheng, Y. L. Hua, J. Wei, and S. G. Yin, “The Relationship of Current Transfer Ratio and Input Light Wavelengths in the Organic Photocoupler”, Applied Physics Letters, vol. 94, pp. 193303 (2009).
22. S. M. L. Nai, J. Wei and M. Gupta, “Effect of Carbon Nanotubes on Shear Strength and Electrical Resistivity of a Lead-free Solder”, Journal of Electronic Materials, vol 37, No. 4, pp. 515-522 (2008) (Shortlisted for IMechE Andrew Fraser Award 2008).
23. S. M. L. Nai, J. Wei and M. Gupta, “Using Carbon Nanotubes to Enhance Creep Performance of Lead-free Solder”, Materials Science and Technology, vol 24, No. 4, pp. 443-447 (2008). 
24. J. Shen, S. Q. Lai, Y. C. Liu, H. X. Gao and J. Wei, “The Effects of Third Alloying Elements on the Bulk Ag3Sn Formation in Slowly Cooled Sn–3.5Ag Lead-Free Solder”, Journal of Materials Science: Materials in Electronics, vol 19, Number 3. pp. 275-280 (2008).
25. K. P. Yung, J. Wei, Z. F. Wang and B. K. Tay, “Effects of under CNT Metallization Layers on Carbon Nanotubes Growth”, Modern Physics Letters B, vol 22, No. 19, pp. 1827-1836 (2008). 
26. X. F. Ang, Z. Chen, C. C. Wong and J. Wei, “Effect of Chain Length in Low Temperature Gold-Gold Bonding by Self-Assembled Monolayers”, Applied Physics Letters, vol 92, Issue 13, pp. 131913 (2008). 
27. X. F. Ang, Z. Chen, C. C. Wong and J. Wei, “Effect of Chain Length in Low Temperature Gold-Gold Bonding by Self-Assembled Monolayers”, Virtual Journal of Nanoscale Science & Technology, vol 17, Iss. 16, (2008).
28. X. F. Ang, F. Y. Li, J. Wei, W. L. Tan, and C. C. Wong, “A Thermal and Passivation Study of Self-Assembled Monolayers on Thin Gold Films”, Thin Solid Films, vol 516, Issue 16, pp. 5721-5724 (2008). 
29. J. W. Ronnie Teo, F. L. Ng, L. S. Kip Goi, Y. F. Sun, Z. F. Wang, X. Q. Shi, J. Wei and G. Y. Li, “Microstructure of Eutectic 80Au/20Sn Solder Joint in Laser Diode Package”, Microelectronic Engineering, vol 85, Issue 3, pp. 512–517 (2008).
30. C. S. Goh, J. Wei, L. C. Lee, M. Gupta, “The Cyclic Deformation Behaviour of Mg-Y2O3 Nanocomposites”, Journal of Composite Materials, vol 42, No. 19, pp. 2039-2050 (2008). 
31. C. S. Goh, J. Wei, L. C. Lee, M. Gupta, “Ductility Improvement and Fatigue Studies in Mg-CNT Nanocomposites”, Composites Science and Technology, Vol 68, Issue 6, pp. 1432-1439 (2008).
32. X. F. Ang, F. Y. Li, W. L. Tan, Z. Chen, C. C. Wong and J. Wei, “Self-Assembled Monolayers for Reduced Temperature Direct Metal Thermocompression Bonding”, Applied Physics Letters, vol 91(06), pp. 061913 (2007).
33. L. Y. Xu, H. Y. Jing, J. Wei and H. Zou, “Evaluation of Interfacial Fracture Behavior of HVAS Coating/Substrate System Using a Local Approach”, Science and Technology of Hybrid Materials, vol 123 pp. 125-132 (2007).   
34. C. S. Goh, J. Wei, L. C. Lee, M. Gupta, “Characterization of High Performance Mg/MgO Nanocomposites”, Journal of Composite Materials, vol 41, No. 19, pp. 2325-2335 (2007). 
35. G. G. Zhang, X. F. Ang, Z. Chen, C. C. Wong and J. Wei, “Critical Temperatures in Thermocompression Gold Stud Bonding”, Journal of Applied Physics, vol 102, Issue 6, pp. 063519 (2007).
36. C. S. Goh, J. Wei, L. C. Lee, M. Gupta, “Properties and Deformation Behaviour of Mg–Y2O3 Nanocomposites”, Acta Materialia, vol 55, Issue 15, pp. 5115-5121 (2007).  
37. C. S. Goh, J. Wei, M. Gupta, “The Static and Cyclic Deformation Behaviours Mg-Y2O3 Nanocomposites”, Key Engineering Materials, The Mechanical Behavior of Materials X, vol 345,pp. 267-270 (2007).
38. S. M. L. Nai, J. Wei and M. Gupta, “Lead-Free Solder Reinforced with Multi-Walled Carbon Nanotubes”, Journal of Electronic Materials, vol 35, No. 7, pp.1518-1522 (2006).    
39. K. P. Yung, J. Wei, B. K. Tay and Z. F. Wang, “Effects of Catalyst Layers on Carbon Nanotubes Growth”, Materials Research Innovations, vol 10, No. 3, pp. 346-351 (2006).
40. C. S. Goh, J. Wei, L. C. Lee, M. Gupta, “Effect of Processing Routes on the Properties of Carbon Nanotubes Reinforced Magnesium”, Science and Technology of Hybrid Materials, vol 111 (2006) 179-182.   
41. J. Wei, “Wafer Bonding Techniques for Microsystem Packaging”, Journal of Physics: Conference Series, vol 34, Issue 1 (2006) 943-948. 
42. C. S. Goh, J. Wei, L. C. Lee, M. Gupta, “Simultaneous Enhancement in Strength and Ductility by Reinforcing Magnesium with Carbon Nanotubes”, Materials Science and Engineering A, vol 423, Issues 1-2, pp. 153-156 (2006).  
43. S. M. L. Nai, J. Wei and M. Gupta, “Development of Lead-Free Solder Composites Containing Nanosized Hybrid (ZrO2 + 8 mol.%Y2O3) Particulates”, Science and Technology of Hybrid Materials, vol 111, pp. 59-62 (2006). 
44. S. M. L. Nai, J. Wei and M. Gupta, “Improving the Performance of Lead-Free Solder Reinforced with Multi-Walled Carbon Nanotubes”, Material Science and Engineering A, vol 423, Issues 1-2, pp. 166-169 (2006).  
45. S. M. L. Nai, J. Wei and M. Gupta, “Influence of Ceramic Reinforcements on the Wettability and Mechanical Properties of Novel Lead-free Solder Composites”, Thin Solid Films, vol 504, Issues 1-2, pp. 401-404 (2006). 
46. C. M. Tan, W. B. Yu and J. Wei, “Comparison of Medium-Vacuum and Plasma-Activated Low-Temperature Wafer Bonding”, Applied Physics Letters, vol 88, Issue 11, pp. 114102 (2006).
47. C. S. Goh, J. Wei, L. C. Lee and M. Gupta, “Development of Novel Carbon Nanotube Reinforced Magnesium Nanocomposites using the Powder Metallurgy Technique”, Nanotechnology, vol 17 Issue 1, pp. 7-12 (2006).
48. X. F. Ang, G. G. Zhang, J. Wei, Z. Chen and C. C. Wong, “Temperature and Pressure Dependence in Thermocompression Gold Stud Bonding”, Thin Solid Films, vol 504, Issues 1-2, pp. 379-383 (2006).
49. L. C. Chin, X. F. Ang, J. Wei, Z. Chen and C. C. Wong, “Enhancing Direct Metal Bonding with self-Assembled Monolayers”, Thin Solid Films, vol 504, Issues 1-2, pp. 367-370 (2006).
50. S. S. Deng, C. M. Tan, J. Wei, W. B. Yu, S. M. L. Nai and H. Xie, “Low-Temperature Sol–Gel Intermediate Layer Wafer Bonding”, Thin Solid Films, vol 496, Issue 2, pp. 560 – 565 (2006).

Conference (Keynote and Invited)

1. J. Wei, C. W. Lee and L. J. Li, Carbon Nanotube Thin Film Transistor Devices, 10th International Workshop on Junction Technology, 10-11 May 2010, Shanghai, China.
2. J. Wei, S. M. L. Nai, X. F. Ang and K. P. Yung, Advanced High Density Interconnect Materials and Techniques, 2009 International Conference on Electronic Packaging Technology & High Density Packaging (ICEPT-HDP), 10-13 August 2009, Beijing, China.
3. M. Gupta, S. M. L. Nai, C.S. Goh and J. Wei, Using Carbon Nanotubes to Enhance the Thermal and Mechanical Properties of Metallic Materials, Materials Science and Technology 2008 (MS&T’08), 5-10 Oct 2008, Pittsburgh, Pennsylvania, USA.
4. J. Wei, High Density Microelectronics Interconnect Materials, 16th International Conference on Processing and Fabrication of Advanced Materials, 17-19 December 2007, Singapore  
5. J. Wei, Wafer Bonding Techniques for Microsystem Packaging, International MEMS Conference, 9-12 May 2006, Singapore.   
6. J. Wei,   Interconnection Material Consideration for Micro/Nanosystems Integration and Packaging, NanoSingapore 2006, IEEE Conference on Emerging Technologies-Nanoelectronics, 10-13 January 2006, Singapore.  
7. J. Wei, C. K. Wong and L. C. Lee, Wafer-Level Micro/Nanosystems Integration and Packaging, Society for Experimental Mechanics, 6th International Symposium on MEMS and Nanotechnology (6th-ISMAN), 6-9 June 2005, Portland, Oregon, USA, pp1-12.
8. J. Wei, C. K. Wong and L. C. Lee, Low Temperature Bonding Process For Wafer-Level MEMS Packaging, Proceedings of 2004 IEEE International Conference on Semiconductor Electronics, (ICSE2004), A19-A26 (2004), 6-9 December 2004, Kuala Lumpur, Malaysia. 

Book Chapter

1. C. S. Goh, M. Gupta, A. E. W. Jarfors, M. J. Tan and J. Wei, Chaper-Magnesium and Aluminium Carbon Nanotube Composites, Trends in Composite Materials and their Design, Trans Tech Publications, Switzerland, Vol. 425 (2010) pp 245-261.
2. X. F. Ang, J. Wei, Z. Chen and C. C. Wong, “Ambient Copper-Copper Thermocompression Bonding using Self-Assembled Monolayers”, Materials and Technologies for 3-D Integration, Book Series: Materials Research Society Symposium Proceedings, Volume: 1112   Pages: 91-99   Published: 2009
3. J. Wei and Z. Sun, “Chapter 21-Wafer bonding”, in Microjoining and Nanojoining, Y. Zhou, Woodhead Publishing Limited, Cambridge, England, pp.633-664, (2008).