TI thin film growth using Molecular Beam Epitaxy (MBE)
MBE operates in ultra-high vacuum to grow high purity films epitaxially from the source materials in the heated effusion cells. This is an excellent way to grow high quality TI thin films over a large area. The advantages of growing TI thin films using MBE mainly includes:
1. Low density of defects.
2. Large size thin films.
3. Accurate doping control.
Our group select mica as the substrate for TI thin film growth as it has the following ideal properties:
1. Van der Waals epitaxy, avoiding lattice mismatch.
2. Chemically and thermally inert.
3. Highly transparent.
4. Flexible.
5. Insulating.
1. Low density of defects.
2. Large size thin films.
3. Accurate doping control.
Our group select mica as the substrate for TI thin film growth as it has the following ideal properties:
1. Van der Waals epitaxy, avoiding lattice mismatch.
2. Chemically and thermally inert.
3. Highly transparent.
4. Flexible.
5. Insulating.
Achievements
We have successfully grown high quality Bi2Te3 thin films on mica for potential optoelectronic applications (Wang, et al. Applied Physics Letters 103, (2013): 031605). They exhibit ultra-smooth surfaces with large-area terraces, high crystalline quality and high surface mobility. Also we observed weak antilocalization (WL) and Shubnikov de Haas oscillation in the Bi2Te3 thin film.
We also grew Cr doped Bi2Te3 on mica and achieved bulk ferromagnetism (Bao, et al. Scientific Reports 2, doi:10.1038/srep00726 ,2012), which breaks the time reversal symmetry (TRS) and opens a surface band gap in the thin films. The crossover between weak antilocalization and weak localization is observed. The thin films have exotic properties for further investigations and applications such as Quantum anomalous Hall Effect.