Low temperature-grown GaAs carrier lifetime evaluation by double optical pump terahertz time-domain emission spectroscopy VALYNN KATRINE MAG-USARA, 1,* STEFAN FUNKNER, 1 GUDRUN NIEHUES, 1 ELIZABETH ANN PRIETO, 2 MARIA HERMINIA BALGOS, 2 ARMANDO SOMINTAC, 2 ELMER ESTACIO, 2 ARNEL SALVADOR, 2 KOHJI YAMAMOTO, 1 MUNEAKI HASE, 3 AND MASAHIKO TANI 1 1 Research Center for Development of Far-infrared Region, University of Fukui, Fukui 910-8507, Japan 2 National Institute of Physics, University of the Philippines, Diliman, Quezon City 1101, Philippines 3 Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8573, Japan * valynn@fir.u-fukui.ac.jp Abstract: We present the use of a “double optical pump” technique in terahertz time-domain emission spectroscopy as an alternative method to investigate the lifetime of photo-excited carriers in semiconductors. Compared to the commonly employed optical pump-probe transient photo-reflectance, this non-contact and room temperature characterization technique allows relative ease in achieving optical alignment. The technique was implemented to evaluate the carrier lifetime in low temperature-grown gallium arsenide (LT-GaAs). The carrier lifetime values deduced from “double optical pump” THz emission decay curves show good agreement with data obtained from standard transient photo-reflectance measurements on the same LT-GaAs samples grown at 250 °C and 310 °C. © 2016 Optical Society of America OCIS codes: (320.7130) Ultrafast processes in condensed matter, including semiconductors; (300.6495) Spectroscopy, terahertz; (300.2140) Emission; (160.6000) Semiconductor materials; (260.7120) Ultrafast phenomena. References and links 1. A. Othonos, “Probing ultrafast carrier and phonon dynamics in semiconductors,” J. Appl. Phys. 83(4), 1789– 1830 (1998). 2. T. Dekorsy, T. Pfeifer, W. Kütt, and H. Kurz, “Subpicosecond carrier transport in GaAs surface-space-charge fields,” Phys. Rev. B Condens. Matter 47(7), 3842–3849 (1993). 3. Y. Shi, X. Xu, Y. Yang, W. Yan, S. Ma, and L. Wang, “Anomalous enhancement of terahertz radiation from semi-insulating GaAs surfaces induced by optical pump,” Appl. Phys. Lett. 89(8), 081129 (2006). 4. H. J. Joyce, C. J. Docherty, Q. Gao, H. H. Tan, C. Jagadish, J. Lloyd-Hughes, L. M. Herz, and M. B. Johnston, “Electronic properties of GaAs, InAs and InP nanowires studied by terahertz spectroscopy,” Nanotechnology 24(21), 214006 (2013). 5. M. C. Beard, G. M. Turner, and C. A. Schmuttenmaer, “Sub-picosecond carrier dynamics in low-temperature grown GaAs as measured by time-resolved THz spectroscopy,” J. Appl. Phys. 90(12), 5915–5923 (2001). 6. S. S. Prabhu, S. E. Ralph, M. R. Melloch, and E. S. Harmon, “Carrier dynamics of low-temperature-grown GaAs observed via THz spectroscopy,” Appl. Phys. Lett. 70(18), 2419–2421 (1997). 7. G. Segschneider, F. Jacob, T. Löffler, H. G. Roskos, S. Tautz, P. Kiesel, and G. Döhler, “Free-carrier dynamics in low-temperature-grown GaAs at high excitation densities investigated by time-domain THz spectroscopy,” Phys. Rev. B 65(12), 125205 (2002). 8. U. Siegner, R. Fluck, G. Zhang, and U. Keller, “Ultrafast high‐intensity nonlinear absorption dynamics in low‐ temperature grown gallium arsenide,” Appl. Phys. Lett. 69(17), 2566–2568 (1996). 9. H. Němec, A. Pashkin, P. Kužel, M. Khazan, S. Schnüll, and I. Wilke, “Carrier dynamics in low-temperature grown GaAs studied by terahertz emission spectroscopy,” J. Appl. Phys. 90(3), 1303–1306 (2001). 10. C. Kadow, S. B. Fleischer, J. P. Ibbetson, J. E. Bowers, and A. C. Gossard, “Subpicosecond carrier dynamics in low-temperature grown GaAs on Si substrates,” Appl. Phys. Lett. 75(17), 2575–2577 (1999). 11. V. Ortiz, J. Nagle, J. F. Lampin, E. Péronne, and A. Alexandrou, “Low-temperature-grown GaAs: Modeling of transient reflectivity experiments,” J. Appl. Phys. 102(4), 043515 (2007). 12. Z. Liliental-Weber, H. J. Cheng, S. Gupta, J. Whitaker, K. Nichols, and F. W. Smith, “Structure and carrier lifetime in LT-GaAs,” J. Electron. Mater. 22(12), 1465–1469 (1993). Vol. 24, No. 23 | 14 Nov 2016 | OPTICS EXPRESS 26175 #275461 http://dx.doi.org/10.1364/OE.24.026175 Journal © 2016 Received 7 Sep 2016; revised 27 Oct 2016; accepted 28 Oct 2016; published 2 Nov 2016