中国物理B ›› 2006, Vol. 15 ›› Issue (10): 2415-2421.doi: 10.1088/1009-1963/15/10/038

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Nonideal effects in quantum field-effect directional coupler

颜晓红1, 谢月娥2, 陈元平3   

  1. (1)College of Science, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China; (2)Institute of Modern Physics and Department of Physics, Xiangtan University, Xiangtan 411105, China; (3)Institute of Modern Physics and Department of Physics, Xiangtan University, Xiangtan 411105, China
  • 收稿日期:2005-06-09 修回日期:2006-06-11 出版日期:2006-10-20 发布日期:2006-10-20
  • 基金资助:
    Project supported by the Project of Hunan Provincial Education Ministry (Grant No 05C103) and the Research Fund of National Education Ministry of China (Grant No 204099).

Nonideal effects in quantum field-effect directional coupler

Xie Yue-E(谢月娥)a), Yan Xiao-Hong(颜晓红)b)†, and Chen Yuan-Ping(陈元平)a)   

  1. a Institute of Modern Physics and Department of Physics, Xiangtan University, Xiangtan 411105, China; b College of Science, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
  • Received:2005-06-09 Revised:2006-06-11 Online:2006-10-20 Published:2006-10-20
  • Supported by:
    Project supported by the Project of Hunan Provincial Education Ministry (Grant No 05C103) and the Research Fund of National Education Ministry of China (Grant No 204099).

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摘要： The nonideal effects in a quantum field-effect directional coupler where two quantum wires are coupled through a finite potential barrier are studied by adopting the lattice Green function method. The results show that the electron energy distribution, asymmetric geometry and finite temperature all have obvious influence on the electron transfer of the coupler. Only for the electrons with energies in a certain region, can the complete periodic transfer between two quantum wires take place. The conductance of these electrons as a function of the barrier length and potential height exhibits a fine periodic or quasi-periodic pattern. For the electrons with energies beyond the region, however, the complete periodic transfer does not hold any more since many irregular oscillations are superimposed on the conductance profile. In addition, the finite temperature and asymmetric geometry both can reduce the electron transfer efficiency.

关键词: nonideal effects, directional coupler, Green function

Abstract: The nonideal effects in a quantum field-effect directional coupler where two quantum wires are coupled through a finite potential barrier are studied by adopting the lattice Green function method. The results show that the electron energy distribution, asymmetric geometry and finite temperature all have obvious influence on the electron transfer of the coupler. Only for the electrons with energies in a certain region, can the complete periodic transfer between two quantum wires take place. The conductance of these electrons as a function of the barrier length and potential height exhibits a fine periodic or quasi-periodic pattern. For the electrons with energies beyond the region, however, the complete periodic transfer does not hold any more since many irregular oscillations are superimposed on the conductance profile. In addition, the finite temperature and asymmetric geometry both can reduce the electron transfer efficiency.

Key words: nonideal effects, directional coupler, Green function

中图分类号:  (Electronic transport in mesoscopic systems)

  • 73.23.-b
73.40.Kp (III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions) 73.63.Nm (Quantum wires)