ThinkQuest Questionnaire

Tell us some general information about yourself/your job.

(Member of the Chinese Academy of Sciences, P.R. China Fellow, TWAS, the Academy of Sciences for the Developing World, Professor (Chair) of Materials Science, Director of the Center Of Super-Diamond and Advanced Films City University of Hong Kong)

Prof. S.T. Lee is currently the Director of the Center Of Super-Diamond and Advanced Films (COSDAF) of City University of Hong Kong, and the Director of the Nano-organic Photoelectronic Laboratory, the Technical Institute of Physics and Chemistry, Chinese Academy of Sciences (TIPC, CAS) in Beijing, P.R. China. He is a Member (Academician) of Chinese Academy of Sciences and Fellow of the TWAS (The academy of sciences for the developing world).

Prof. Lee has filed over 16 US patents, published 6 book chapters, and over 500 papers in peer-reviewed SCI journals including 5 papers in Science and Nature. He received the Humboldt Senior Research Award (2001), Croucher Senior Research Fellowship of the Croucher Foundation (2002), and two State Natural Science Awards (second prize) in 2002 and 2005 respectively. His research interests include nanoscience and nanotechnology, organic electroluminescence and optoelectronics, thin films and super-hard coatings, surface science and modification. Prof. Lee is currently the Associate Editor of Applied Physics Letters, Associate Editor of Diamond and Related Materials, Regional Editor for Asia of Physica Status Solidi, and the Advisory Editorial Board of Advanced Functional Materials and Applied Nanoscience.

How would you define nanotechnology?

Is there anything that you can tell us about your work in the field of nanotechnology?

Fabrication and characterization of inorganic nanomaterials: My group has established the infrastructure needed for growth (including furnace methods, laser ablation, and plasma CVD methods), characterization of nanostructures (HRTEM, HRSEM, STM/STS/AFM), properties (optical - PL and lasing, electrical – I-V measurements, field emission, chemical, i.e. sensitivity to gases such as NH3, mechanical etc.), and computation simulation and modeling. We are working on Si nanowire growth and its production in bulk quantities. Our group invented oxide-assisted growth (OAG) as a general (patented in US) method, different than metal-catalyst VLS growth, for nanomaterials synthesis. We also demonstrated the use of OAG to grow nanowires of a host of other inorganic materials with a variety of morphologies (wires, nano-ribbons, etc). We created the world’s finest silicon nanowire, about one nanometer, or 50,000 times smaller than a strand of human hair, an achievement that made the front cover of Science magazine. The significance of this breakthrough is that it provides the foundations for creating smaller and smaller nanomaterials and devices, and it has led to many interesting observations and discoveries. For example, we provided the first direct experimental evidence of the ‘quantum confinement effect’ in silicon nanowires. This is when the silicon nanowire diameter decreases, its band gap energy increases. Scientists have known about this phenomenon for a long time, but never seen it in silicon! We achieved this major breakthrough using STM that can look at features smaller than atomic size or 0.1 nanometre. Our work in this area has been featured in the magazines Science and Nature, an indication of its significance.

Nanodiamond is one of the most promising nanomaterials due to diamond’s unique set of extreme properties. We are working on both modeling and understanding of diamond nucleation and growth and the manipulation of different nanodiamond forms (different crystalline sizes, nanodiamond/a-C composites). We also developed advanced techniques to nanostructure single crystalline sharp diamond tips with sizes of a few tens of nanometers.

Nanostructured coatings – My group is working on growth and characterization of cubic boron nitride (cBN) coating. We demonstrated how carbon and BN films can be manipulated to form amorphous structures with tuned local configurations (sp3 and sp2 fractions) as well as form multi-walled carbon tubes,

Oriented graphene sheets with different, controllable orientations and even crystalline forms of different sizes.

If you only had a few sentences to explain the usefulness and importance of nanotechnology to the general public, what would you say?

Reduction in feature size results in fascinating properties, including structural, chemical, physical, mechanical, electronic, optical, magnetic, etc., which are expected to lead to innovative practical applications. Quantum mechanical effects, exhibited by nanosized features, offer an entirely different thinking in the design and fabrication of electronic and optoelectronic devices. Novel nanoscience phenomena discovered in chemistry and biology can find important applications, such as nanosensors and nanoprobes.

What reasonable advances do you think we (the world) will make in the field of nanotechnology in the next 10 years? 20 years? 50?

In the next 10 years: Nano-coating in clothing, UV and chemical sensors, nano-filter for water purification, OLED as solid-state lighting, nanobiotechnology like drug delivery, CNT field emission display.

In next 20 years: Biological and biomedical sensors to detect virus and cancers, photonic devices like nano-scale laser

In next 50 years: nano-electronics which make super-computer/computer smaller, biomedical devices to cure cancer

What are some of the top challenges in the field of nanotechnology right now?

• Difficult to manipulate

• Lifetime of the device

• Physics not well known

What are some research projects (and applications) that your department is currently working on?

• Growth and characterization of II-VI semiconducting nanomaterials for sensors, electronic devices and laser

• Growth and characterization of III-V semiconducting nanomaterials for sensors and electronic devices

• Growth and characterization of carbon and silicon based nanomaterials

• Growth and characterization of nanostructural functional coatings

• Nanodiamond

• Fabrication of patterned quantum dots

• OLED fabrication

• Nanocomposite

What areas of science should people study if they want to go into nanotechnology?

People should study nano surface engineering if they want to go into nanotechnology. Nano surface engineering is an essential part of any nanomaterial program. There are two basic approaches in nanofabrication: (1) the “build-down” or “top-down” approach by nanostructuring deposited films on a substrate, which is an extension of the current semiconductor technology, and (2) the “build-up” or “bottom-up” approach by assembling pre-fabricated (free-standing) nanocomponents (clusters, wires, or tubes). Patterning and chemical functionalization are another important steps in the practical utilization of nanomaterials. In particular chemical functionalization is needed for manipulating the wire chemistry and biological behavior to be able to attach specific chemical molecules or biological units (e.g. DNA) to serve applications such as chemical and biological sensing.

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