3维拓扑绝缘体中存在着奇异的表面输运性质，但是体载流子的信号往往会在输运测量中占主导地位，这使得对3维拓扑绝缘体表面态的直接探测非常困难,而测量Shubnikov-de Hass (SdH)振荡却能提供探测表面态的有效途径。首先，在不同磁场方向上测量的p型（或n型）Bi2Se3纳米片中的SdH振荡表明了其2维特性，进一步分析得到接近π/2 的Berry相位也证明了振荡起源于表面狄拉克费米子。结合对温度依赖SdH振荡的标准分析，得到了包括二维载流子浓度，散射时间，回旋质量和表面电导等一系列表面态信息。此外，低磁场下的霍尔测量给出了体载流子浓度，结合two-band模型，解释了霍尔测量中的非线性行为，并计算得到表面电导约占总电导的14%。最后对温度依赖的电阻进行测量，在低温（<30K）下显示出很强的电子-电子相互作用

Three-dimensional (3D) topological insulators are predicted to present unique surface transport phenomena, but relativity large residual bulk carriers that dominate the transport signal make the transport study to the surface states a serious challenge in real 3D topological insulators materials. However, the measurement of Shubnikov-de Hass (SdH) oscillations can provide us an efficient tool to study the surface states. First, we measured the SdH oscillations in the p-type (or n-type) Bi2Se3 nano-flakes on different magnetic field direction to show the two-dimensional (2D) nature of these oscillations. More important, a near half π Berry phase was proved to exist in the 2D oscillations, and spin-Zeeman effect was used to explain the deviation from the ideal π Berry phase. Then, standard analysis of temperature dependent oscillations enable us to extract their carrier concentration, scattering time, and surface conductance and so on. The cyclotron mass and Fermi energy level obtained here are in agreement with the results in angle-resolved photoemission spectroscopy (ARPES) study to Bi2Se3. Furthermore, we have been able to clarify both the bulk and surface transport channels and establish a comprehensive understanding of the transport in this material by Hall measurements and two band model. Finally, in the temperature dependent resistance measurement a weak increasing tendency of the resistance in low temperature region is observed and is believed that it is caused by electron-electron interaction.