中国物理B ›› 2012, Vol. 21 ›› Issue (10): 104101-104101.doi: 10.1088/1674-1056/21/10/104101

• ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS • 上一篇    下一篇

Finger capacitance of a terahertz photomixer in low-temperature-grown GaAs using the finite element method

陈龙超, 范文慧   

  1. State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi'an 710119, China
  • 收稿日期:2012-01-15 修回日期:2012-03-12 出版日期:2012-09-01 发布日期:2012-09-01

Finger capacitance of a terahertz photomixer in low-temperature-grown GaAs using the finite element method

Chen Long-Chao (陈龙超), Fan Wen-Hui (范文慧)   

  1. State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi'an 710119, China
  • Received:2012-01-15 Revised:2012-03-12 Online:2012-09-01 Published:2012-09-01
  • Contact: Fan Wen-Hui E-mail:fanwh@opt.ac.cn

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摘要： Interdigitated finger capacitance of a continuous-wave terahertz photomixer is calculated using the finite element method. For the frequently used electrode width (0.2 μm) and gap width (1.8 μm), the finger capacitance increases quasi-quadratically with the number of electrodes increasing. The quasi-quadratic dependence can be explained by a sequence of lumped capacitors connected in parallel. For a photomixer composed of 10 electrodes and 9 photoconductive gaps, the finger capacitance increases as the gap width increases at a small electrode width, and follows the reverse trend at a large electrode width. For a constant electrode width, the finger capacitance first decreases and then slightly increases as the gap broadens until the smallest finger capacitance is formed. We also investigate the finger capacitances at different electrode and gap configurations with the 8 μm ×8 μm photomixer commonly used in previous studies. These calculations lead to a better understanding of the finger capacitance affected by the finger parameters, and should lead to terahertz photomixer optimization.

关键词: terahertz photomixer, continuous-wave, interditated finger capacitance, finite element method

Abstract: Interdigitated finger capacitance of a continuous-wave terahertz photomixer is calculated using the finite element method. For the frequently used electrode width (0.2 μm) and gap width (1.8 μm), the finger capacitance increases quasi-quadratically with the number of electrodes increasing. The quasi-quadratic dependence can be explained by a sequence of lumped capacitors connected in parallel. For a photomixer composed of 10 electrodes and 9 photoconductive gaps, the finger capacitance increases as the gap width increases at a small electrode width, and follows the reverse trend at a large electrode width. For a constant electrode width, the finger capacitance first decreases and then slightly increases as the gap broadens until the smallest finger capacitance is formed. We also investigate the finger capacitances at different electrode and gap configurations with the 8 μm ×8 μm photomixer commonly used in previous studies. These calculations lead to a better understanding of the finger capacitance affected by the finger parameters, and should lead to terahertz photomixer optimization.

Key words: terahertz photomixer, continuous-wave, interditated finger capacitance, finite element method

中图分类号:  (Electrostatics; Poisson and Laplace equations, boundary-value problems)

  • 41.20.Cv
02.70.Dh (Finite-element and Galerkin methods) 42.72.Ai (Infrared sources)