相干输运中的接点问题

Role of contacts in the conherent transport

为了研究介观体系的相干输运中接点的重要作用,采用一简单的纳米单势垒"二维-一维-二维"(2D-1D-2D)模型,应用散射矩阵方法和托马斯-费米近似,计算了体系透射率和在直流电压下电势分布.结果表明:1)接点对其透射率有显著的影响;2)电势降落表现的电导性质违背了与经典串联电路中等价的基尔霍夫定律.因此介观体系中各器件与接点间是量子相干的,考虑接点问题有利于对介观体系相干输运更为深入的研究.

In order to study the role of contacts in the coherent transport of mesoscopic structure systems, a 2D-1D-2D model of nanosized single-barrier system is considered, which includes a single-barrier structure conductor with two reservoirs. Basing on the scattering-matrix method and the Thomas-Fermi approximation, we have calculated the transmission probability and the distribution of internal potential when a dc voltage is applied to the system. The results show that ： （ 1 ） the contacts can produce significant effects on the transmission probability; （2） the behaviors of conductance and the distribution of internal potential differ from the usual transport conductance give by the Kirchhoff＇s laws. Therefore We conclude that since contacts and the mesocopic systems am quantum coherent, the role of contacts is important for in-depth investigation of the transport in mesoscopic systems.