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Post date: Sep 25, 2013 4:27:10 AM
Topological insulators
An ordinary insulator such as glass cannot conduct electricity because electrons are not free to move through the material, but physicists have recently discovered a special type of insulator that behaves somewhat differently. The electrons inside or in the bulk of these ‘topological
insulators’ behave like the electrons in conventional insulators. However, topological insulators have surface states in which electrons can flow as easily as in a metal. A topological insulator can thus be thought of as a glass that is coated with a very thin (~1 nm thick) layer of metal on its surface (or along its edges for a two-dimensional topological insulator). More importantly, these surface or edge states possess exotic properties that could prove useful in applications such as error-tolerant quantum computation and low-power electronics. [1-4]
Low dimensional nanoelectronics (Experiment)
Now, I'm working on the fabrication of MoS2 (molybdenum disulfide) double-gate FET, and expecting to measure and design methodology to improve the mobility of this device. The motivation is that MoS2 (molybdenum disulfide) FET has shown high on/off ratio,[6] which could potentially be used as low power switching devices. High-k materials, such as Al2O3 (aluminum oxide) and HfO2 (hafnium oxide) will be used as insulators, and four terminals Hall bars are used to measure the channel mobility. At the same time, the electric, thermal and electro-magnetic properties of MoS2 (molybdenum disulfide) are investigated.
After doing this basic work, floating memory combining graphene or ferroelectric materials and MoS2 would be surveyed, in which we are take advantage of high on/off ratio related with MoS2 FET and electron accumlation related with graphene or ferroelectric materials. [7]
Low dimensional nanoelectronics (Modeling)
With device dimensions 22 nm or below, materials modeling or computational materials is becoming a critical part of technology development and is needed to address several components of technology development:
1) Synthesis to structure & composition, especially on the interfaces and multi-interface material structures;
2) Properties of these structures including interface physics of state transition, defects states, etc. In addition, non-equilibrium properties of these structures such as conductance, mobility;
3) Probe interactions with samples to enhance quantification of structure, composition, and properties. [8]
Now, I'm working on NEGF simulation of vertical graphene heterosturctures sandwiched with MoS2 (molybdenum disulfide) or h-BN (hexagonal boron nitride) tunneling FET.[9]
1. Qi, X-L. & Zhang, S-C. Phys. Today 63, 33–38 (January 2010).
2. Hasan, M. Z. & Kane, C. L. Rev. Mod. Phys. 82, 3045–3067 (2010).
3. Moore, J., Nature Phys. 5, 378–380 (2009).
4. Qi-Kun Xue, Nature Nano. 6, 197-198 (2011).
5. Xiu, F. et al. Nature Nanotech. 6, 216–221 (2011).
6. B. Radisavljevic et al. Nature Nano. 6, 147–150 (2011)
7. Yi Zheng et al. Applied Physics Letter. 94, 163505 (2009)
8. International Technology Roadmap for Semiconductors (ITRS), 2011. [Online]. Available:http://public.itrs.net/reports.html
9. L. Britnell et al. Science, Vol. 335 no. 6071 pp. 947-950 (2012)
Original Link: http://blog.sina.com.cn/s/blog_5d650197010117dd.html
Figure 1 | A FET in which the channel is a topological insulator nanoribbon. [4-5]
Figure 2 | Illustration of vertical graphene tunneling FET. [J.K Ding & Q.M. Shao]
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