| With the discovery of the quantum Hall effect, topological insulators began to enter the field of vision of scientists. Since the topological insulator is a special quantum state of matter, so its conductive properties is completely different from that of conventional conductors and insulators. For example, the inner material is an insulator,and the surface exhibits properties of the conductor. Bismuth telluride, as the most representative topological insulator material, has the highest figure of merit at room temperature, and because of its relatively narrow band gap, it has a very high applicable value in thermoelectric material, phase change material, and topological insulator. It has raised more and more scientists’ attention.In this study, firstly by physical vapor deposition method, bismuth telluride nano-materials was prepared, and effect of the experimental conditions on bismuth telluride morphology was discussed. Experimental results showed that, under certain conditions, the higher the deposition temperature is, the more easily the nanowires form.And faster the gas flow rate is, the more easily the nanowires form. If lattice parameter of the deposited substrate and the lattice parameters of bismuth telluride have a difference, the greater the difference is, the more easily the nanowires deposited. And the farther the deposition is, the worse the deposition effect is.Based on first-principles knowledge, Materials Studio 7.0 software was used to conduct computer simulation related to first-principles. The "Reflex" modules pattern was used to simulate bismuth telluride diffraction, the simulation results showed that,within the accuracy allowable range, simulation results and experimental results were in good agreement. "CASTEP" modules were used to simulate bismuth telluride analog electronic energy band diagram. The analysis reveals that bismuth telluride band gap energy is 0.427 eV, proving that bismuth telluride is a narrow bandgap semiconductor.Based on knowledge of molecular dynamics, Materials Studio 7.0 software was used to conduct simulation related to molecular dynamics. Using molecular dynamics module The "Discover" modules pattern was used to simulate the mechanical properties of the elastic constants of bismuth telluride, the simulation results show that, the stiffness matrix simulated of bismuth telluride meet the the form of trigonal and as the temperature rises(from 0K to 600K), Poisson’s ratio of bismuth telluride nanosheets was an increasing trend, while the elastic modulus, bulk modulus and shear modulus with increasing temperature and decreasing, and in line with the law of linear variation. |
