Excitation wavelength dependence of terahertz emission from semiconductor surface

Masato Suzuki and Masayoshi Tonouchi

Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871, Japan

Ken-ichi Fujii

Department of Physics, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan

Hideyuki Ohtake and Tomoya Hirosumi

Aisin Seiki Co., Ltd., Kojiritsuki, Hitotsugi-cho, Kariya 448-0003, Japan

(Received 30 January 2006; accepted 1 July 2006; published online 30 August 2006)

The authors have measured terahertz radiation from InSb, InAs, and InGaAs excited by femtosecond optical pulses at wavelengths of 1560, 1050, and 780 nm. The amplitude of the terahertz field strongly depends on the pump wavelengths. Among the materials, the InSb emitter shows the largest terahertz emission amplitude at high power 1560 nm excitation, whereas 780 nm excitation provides the weakest. With increasing photon energy, the increase in emission amplitude from InAs is less as compared to that from InGaAs. The decrease from InSb and InAs originates in low mobilities of L or X valley carriers generated by intervalley scatterings. ©2006 American Institute of Physics

doi:10.1063/1.2338430