Spectral dependencies of terahertz emission from InAs and InSb

Spectral dependences of the THz radiation from the laser-illuminated surfaces of InAs and InSb have been investigated experimentally at high optical fluences for the laser wavelengths ranging from 0.6 to 2 mu m. Efficient THz generation was discovered in the excitation range around 1.6 mu m. The influence of the intervalley scattering was clearly evidenced. The energy position of the subsidiary conduction band valleys was evaluated from this study to be equal 1.08 and 0.53 eV for InAs and InSb, respectively. It has been concluded that THz emission at high excitation fluencies is dominated by the shift current effect. (c) 2005 American Institute of Physics.