Exploration And Research On Micro-Devices Based On Quantum Anomalous Hall Effect

After the discovery of quantum Hall effect at1980, scientists have always been trying to find a way to achieve the quantum Hall state without an external magnetic field. Later the predictions and experimental realization of topological insulator let people see the hope, the scientists predicted that within magnetically doped topological insulator, the Dirac point of the surface state opens an energy gap. If adjust the Fermi surface of the material to the energy gap, there may be an experimental observation of the quantum Hall effect under a zero magnetic field: quantum anomalous Hall effect. Based on this background, the main work of this paper can be divided into two main parts:(1) The work of experimental realization of QAHE I participated in is based on the Cr0.15(Bi0.1Sb0.9)1.85Te3films grown on SrTiO3(STO)(111) substrates. At zero magnetic field, the back gate voltage tuned anomalous Hall resistance reaches the h/e2quantum platform while the longitudinal resistance drops down to0.098h/e2. Under a strong magnetic field the longitudinal resistance disappears completely, whereas the anomalous Hall resistance remains the quantized value of h/e2. There is no doubt that the experimental results prove our conclusions.(2) In order to solve problems that the QAHE samples are usually deteriorated by the chemicals used in the photolithography process, we proposal a new method to fabricate micro-devices of topological insulator. We pre-pattern the STO substrate with photolithography. Then we grow topological insulator films onto Hall bar-shaped plateaus pre-lithographed on SrTiO3substrate. The AFM images and transport measurements show that topological insulator films grew by this method can keep the similar character of epitaxial topological insulator films on ordinary SrTiO3substrates.