IEEE Journal of Quantum Electronics, Vol. 34, No. 1, pp. 171-178, January 1998.

(Manuscript received August 22, 1996; revised September 10, 1997)

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The phenomena involved in the subpicosecond electrical pulses generated by edge illumination of a charged coplaner transmission line on silicon substrate are investigated theoretically using a two-dimensional numerical model.  The calculated terminal current, which is related to the observed electrical signal, is interpreted as being due to the dielectric relaxation of the space-charge field based on an equivalent circuit model.  The pulse dependence (including amplitude, delay, rise time, and shape) on the wavelength of the laser source is investigated in terms of light penetration and the generated photocarriers.  The frequency limit of the laser pulse train is determined theoretically for different carrier lifetimes.  The simulation results are in qualitative agreement with experimental observations, and the dielectric-relaxation interpretation is consistent with other theories based on the full-wave analysis and the Monte Carlo model.

• [1] D. Krokel, D. Grischkowsky, and M. B. Ketchen, “Subpicosecond electrical pulse generation using photoconductive switches with long carrier lifetimes,” Appl. Phys. Lett., vol. 54, pp. 1046–1047, 1989.
• [2] U. D. Keil and D. R. Dykaar, “Electro-optic sampling and carrier dynamics at zero propagation distance,” Appl. Phys. Lett., vol. 61, pp. 1504–1506, 1992.
• [3] C.-C. Wang, M. Currie, R. Sobolewski, and T. Y. Hsiang, “Subpi-cosecond electrical pulse generation by edge illumination of silicon and indium phosphide photoconductive switches,” Appl. Phys. Lett., vol. 67, pp. 79–81, 1995.
• [4] S. Alexandrou, C.-C. Wang, R. Sobolewski, and T. Y. Hsiang, “Generation of subpicosecond electrical pulses by nonuniform illumination of GaAs transmission-line gaps,” IEEE J. Quantum Electron., vol. 30, pp. 1332–1338, 1994.
• [5] —, “Subpicosecond electrical pulses generation in GaAs by nonuni-form illumination of series and parallel transmission line gaps,” in Conf. Ultrafast Electronics and Optoelectronics, San Francisco, CA, 1993, paper ME10.
• [6] U. D. Keil and D. R. Dykaar, “Ultrafast pulse generation in photoconductive switches,” IEEE J. Quantum Electron., vol.32, pp.1664–1671,1996.
• [7] E. Sano and T. Shibata, “Mechanism of subpicosecond electrical pulse generation by asymmetric excitation,” Appl. Phys. Lett., vol. 55, pp. 2748–2750, 1989.
• [8] S. E. Ralph and D. Grischkowsky, “Trap-enhanced electric fields in semi-insulators: The role of electrical and optical carrier injection,” Appl. Phys. Lett., vol. 59, pp. 1972–1974, 1991.
• [9] X. Zhou, S. Alexandrou, and T. Y. Hsiang, “Monte Carlo investiga-tion of the intrinsic mechanism of subpicosecond pulse generation by nonuniform illumination,” J. Appl. Phys., vol. 77, pp. 706–711, 1995.
• [10] X. Zhou, “Numerical physics of subpicosecond electrical pulse genera-tion by nonuniform gap illumination,” IEEE J. Quantum Electron., vol. 32, pp. 1672–1679, 1996.
• [11] —, “On the physics of femto-second electrical pulse generation in transmission-line gaps,” Optoelectronics—Devices and Technologies, vol. 10, pp. 491–504, 1995.
• [12] L. S. Seah and C. J. Yap, “Semiconductor device characterization with TCAD,” Final Year Project Rep., School of Electrical and Electronic Engineering, Nanyang Technological Univ., Singapore, 1995–1996, P6080.
• [13] S. Alexandrou, R. Sobolewski, and T. Y. Hsiang, “Time-domain char-acterization of bent coplanar waveguides,” IEEE J. Quantum Electron., vol. 28, pp. 2325–2332, 1992.
• [14] D. H. Auston, “Impulse response of photoconductors in transmission lines,” IEEE J. Quantum Electron., vol. QE-19, pp. 639–648, 1983.
• [15] MEDICI, Technology Modeling Associates, Inc., Palo Alto, CA, 1994.
• [16] D. M. Caughey and R. E. Thomas, “Carrier mobilities in silicon empirically related to doping and field,” Proc. IEEE, vol. 55, pp. 2192–2193, 1967.
• [17] K. A. Jones, Introduction to Optical Electronics. New York: Harper & Row, 1987, p. 173.

1. [11] Shi-Hsiang Lu, Jun-Liang Li, Jian-Shen Yu, Sheng-Fu Horng, and C. C. Chi, "Observation of terahertz electric pulses generated by nearly filled-gap nonuniform illumination excitation," Appl. Phys. Lett., Vol. 77, No. 24, pp. 3896-3898, Dec. 2000. 
2. [39] J. F. Holzman, F. E. Vermeulen, and A. Y. Elezzabi, "Ultrafast photoconductive self-switching of subpicosecond electrical pulses," IEEE J. Quantum Electron., Vol. 36, No. 2, pp. 130-136 Feb. 2000. 
3. [] X. M. Zheng, C. V. McLaughlin, P. Cunningham, and L. M. Hayden, "Organic broadband terahertz sources and sensors," J. Nanoelectron. Optoelectron., Vol. 2, No. 1, pp. 58-76, Apr. 2007

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