Song J-T, Li Y-X, Sun Q-F
Department of Physics and Hebei Advanced Thin Film Laboratory, Hebei Normal University, Hebei 050024, People's Republic of China.
J Phys Condens Matter. 2014 May 7;26(18):185007. doi: 10.1088/0953-8984/26/18/185007. Epub 2014 Apr 23.
We investigate electron transmission coefficients through quantum wells and quantum superlattices on topological insulator surfaces. The quantum well or superlattice is not constituted by general electronic potential barriers but by Fermi velocity barriers which originate in the different topological insulator surfaces. It is found that electron resonant modes can be renormalized by quantum wells and more clearly by quantum superlattices. The depth and width of a quantum well and superlattice, the incident angle of an electron, and the Fermi energy can be used to effectively tune the electron resonant modes. In particular, the number N of periodic structures that constitute a superlattice can further strengthen these regulating effects. These results suggest that a device could be developed to select and regulate electron propagation modes on topological insulator surfaces. Finally, we also study the conductance and the Fano factor through quantum wells and quantum superlattices. In contrast to what has been reported before, the suppression factors of 0.4 in the conductance and 0.85 in the Fano factor are observed in a quantum well, while the transport for a quantum superlattice shows strong oscillating behavior at low energy and reaches the same saturated values as in the case of a quantum well at sufficiently large energies.
我们研究了通过拓扑绝缘体表面上的量子阱和量子超晶格的电子传输系数。量子阱或超晶格并非由一般的电子势垒构成，而是由源自不同拓扑绝缘体表面的费米速度势垒构成。研究发现，电子共振模式可被量子阱重整化，而量子超晶格对其重整化作用更明显。量子阱和超晶格的深度与宽度、电子入射角以及费米能量可用于有效调节电子共振模式。特别地，构成超晶格的周期性结构数量N可进一步增强这些调节效果。这些结果表明，可以开发一种器件来选择和调节拓扑绝缘体表面上的电子传播模式。最后，我们还研究了通过量子阱和量子超晶格的电导和法诺因子。与之前报道的情况不同，在量子阱中观察到电导的抑制因子为0.4，法诺因子的抑制因子为0.85，而量子超晶格的输运在低能量时表现出强烈的振荡行为，在足够大的能量下达到与量子阱情况相同的饱和值。
