Gate-Tunable Transport Properties of Ultra-Thin Topological Insulator Thin Film and Electrical Detection of Spin Signal
| Autor: | Chun-Ming FanChiang, 范姜群名 |
|---|---|
| Rok vydání: | 2016 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 104 Three-dimensional topological insulator Bi2Se3 has natural Se vacancy and causes high intrinsic n-type carrier concentration. In order to research the surface state, we doped Sb into Bi2Se3 to tune down the carrier concentration. We successfully grew the ultra-thin Sb-doped Bi2Se3 film on sapphire and SrTiO¬3 (STO) substrate, do the basic electrical properties on sapphire and gate-tunable transport properties on STO. An extremely large change of the sheet resistance in ultra-thin film is observed owing to the surface gap opening. The on-off ratio is about 14000%. On the other hand, we study the spin valve device which can electrical detect the current-induced spin polarization due to spin-momentum locking. The barrier between topological insulator and ferromagnetic layer is the key point to detect the signal. By selecting a great barrier condition, we can observe the hysteresis-like spin signal from surface state. If we can combine the spin valve device with back gate and ultra-thin topological insulator film, the mechanism of spin-transistor may be realized. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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