Structure dependence of the waveforms of THz radiation from GaAs-based photovoltaic devices

We report the time-profile of the THz wave from GaAs-based photovoltaic devices depending on its structure. Bias dependence of the THz waveforms indicates that the picosecond drift current depends on the device structure even with the same depletion layer condition. This result is critical for the photovoltaic device characterization with the measurement of the THz radiation.