THz radiation from In[x]Ga[1-x]As (x=1, 0.53, 0.60) excited by femtosecond lasers at wavelengths of 1560, 1050, and 780 nm

Terahertz (THz) radiation from n-InAs, unimplanted In_xGa_1-xAs (x≡0.53,0.60), and Fe-implanted In_xGa_1-xAs (x≡0.53,0.60) was investigated using the femtosecond pulses of wavelength 780, 1050, and 1560 nm. The frequency bandwidths of THz waves from the 780-, 1050-, and 1560nm-excited InAs are achieved to be 4 THz. For the unimplanted InGaAs emitter, THz radiation mechanisms of surface field carrier acceleration and photo-Dember effect can be separated by 780 and 1560 nm excitation. The lattice-mismatched InGaAs emitter is more efficient THz emitter than the lattice-matched InGaAs emitter. THz radiation from 780-nm-excited InGaAs was suppressed by Fe implantation due to short absorption depth of the 780 nm light.