Terahertz emission from MBE-grown InAs and GaAs thin films on Si substrates excited in the transmission-geometry

Terahertz radiation was generated from femtosecond laser-pumped MBE-grown InAs and GaAs thin films on Si substrates. Results showed that InAs/Si and GaAs/Si films can be excited in both reflection and transmission geometries. The InAs/Si film exhibited weaker emission for both excitation cases but the absence of outstanding spectral features in its emission spectrum makes it a more viable THz spectroscopy source. Moreover, excitation fluence dependence data showed that the InAs/Si film saturates more easily; which is primarily due to the laser’s limited penetration depth in this sample.