Low-Temperature Electron Transport Properties Of Topological Insulator Nanowires

Topology insulators?TIs? are a new class of materials which attract people's attention due to possessing an insulating bulk gap and gapless surface states. Moreover, with the property of helical electron that the electron's spin and momentum are locked. The Berry phase caused by the spin-helical surface states, which suppresses the backscattering effectively and hence prevents to localization regardless of the strength of disorder. The spin and momentum locked to the surface not only provide a novelty system to study fundamental physics, but also has potential applications in spintronics and dissipationless electronics.However, the large concentrations of bulk carriers make the Fermion level pined to the conduction band ?CD? due to the intrinsic Se vacancies and it leads to the signals from the surface states?SS? are difficult to acquire by transport measurements. Moreover, it is arduous to tune the chemical potential by the electrostatic gating techniques available for Bi₂Se₃. So in this paper, we use a nanowire which possess higher surface volume ratio and through chemical doping decreases the density of carriers. On the basis of dopedBi₂Se₃ nanowire, we study the 1/f noise of surface electronic states and the low temperature electron transport properties of topological insulator nanowires.Chapter 1 provides a brief introduction of topological insulator and the research states at home and abroad.Chapter 2 is dedicated to the synthesis of high quality topological insulators nanowires by chemical vapor deposition and the fabrication of nanowire device through micfabrication technology.In chapter 3 we have tune the chemical potential of Bi₂Se₃ nanowire by the electrostatic gating techniques to suppressed the bulk conductance. Moreover discuss the measurement of carrier density for different dimensional materials. We through two way acquire effective gating ability, including the fabrication of high-k dielectric layer and chemical doping.In Chapter 4 We discusses the experiment about low-frequency noises based on Sb-doped Bi₂Se₃ nanowire field effect transistor ?FET?. We tune the Fermi level to dirac point and measure the current noise which is aroused by topological insulator surface electron and laid a certain foundation for future topological insulator electronic device.In chapter 5 we explore the low temperature electron transport properties of topological insulator nanowires, and find a hysteretic behavior whose magnitude depending on the magnetic field sweep rate and temperature, similar to member effect and try to give some explains.Chapter 6 is the summary and prospect.