Molecular beam epitaxy, MBE- I
The front view (left) and the back view (right) of our MBE system. (A) is the load-lock chamber, (B) is the growth chamber, (C) is the Knudsen cell, (D) is the RHEED screen, (E) is the electron source of RHEED, (F) is the cryo pump and ion pump and (G) is the thickness monitor.
工作原理：
In MBE system, we put material in Knudsen cell (K-cell), which heat the material source indirectly by tungsten filament to effuse the material. While the molecular beam contact with the substrate, molecules without polarities will induce some dipole moment by thermal disturbance and this weak polarity will deposit on the substrate. On the other hand, molecules with polarities will possess stronger adsorbability. We can classify the mechanism of deposition in detail as follow
Scheme of deposition process. (a) Physisorption (b) Reflection (c) Diffusion (d) Desorption (e) Chemisorption.
研究方向：
Topological insulator transport, (Bi2Se3, Bi2Te3, Sb2Te3, BiTeSe, BiSbSe, SbTeSe)
Topological insulator phase transition, (BiSbSe)
Topological insulator device. (Bi2Se3, BiSbSe)
3-D topological insulators (TIs) such as Bi2Te3, Bi2Se3 and Sb2Te3 and their alloys are the new class of materials which recently gain a lot of research attention due to their unique surface properties. Intrinsically, they possess bulk insulating states with narrow band gap while simultaneously the surface presents metallic states which are topologically protected due to the strong spin-orbit coupling. This topological surface state (TSS) has Dirac fermions linear dispersion with high mobility. Furthermore, the electron spins are tightly locked with the momentum, and thus the elastic backscattering is prohibited in the absence of magnetic impurities.
These unique surface states make them a promising candidates for high speed/low power (low energy consumption) electronics devices. Beside the superior transport properties, the spin-momentum locking mechanism enables TIs support spin-polarized surface current and potentially used for all-electrical controlled spintronics devices.
In order to know more topological insulators mechanism to develop device is significant, our major studies are focus on topological insulators on device, including single gate, dual-gate, spin valve and normal insulator/topological insulators bi-layer issue.
研究成員：
Yu-Hung Liu
Yun-Hong Li
Ya-chen Jhong
Jhih-jie Lu
