Transport through quantum wells and superlattices on topological insulator surfaces
Transport through quantum wells and superlattices on topological insulator surfaces
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DOI：
10.1088/0953-8984/26/18/185007
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发表时间：
2014-05
期刊：
影响因子：
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通讯作者：
Juntao Song;Y.-X. Li;Q.-F. Sun
中科院分区：
文献类型：
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作者：
Juntao Song;Y.-X. Li;Q.-F. Sun
我们研究了电子在拓扑绝缘体表面上通过量子阱和量子超晶格的透射系数。量子阱或超晶格不是由一般的电子势垒构成的，而是由起源于不同拓扑绝缘体表面的费米速度势垒构成的。发现电子共振模式可以通过量子阱进行重整化，而量子超晶格的重整化效果更明显。量子阱和超晶格的深度和宽度、电子的入射角和费米能量可以有效地调节电子的共振模式。特别是，N个周期结构组成一个超晶格可以进一步加强这些调节作用。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，我们还通过量子阱和量子超晶格研究了电导和Fano因子。与之前的报道相反，在量子阱中观察到电导的抑制因子为0.4，Fano因子为0.85，而量子超晶格的输运在低能量下表现出强烈的振荡行为，并达到与足够大能量的量子阱相同的饱和值。
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.