Thz radiation of photoconductive antennas based on $\{$LT-GaAs/GaAs:Si$\}$ superlattice structures

A material in the form of a multilayer structure based on low-temperature LT-GaAs grown on (111)A-oriented substrates is proposed for fabrication of THz photoconductive antennas. These structures contain active LT-GaAs layers and doping acceptor GaAs:Si-based layers. At the optical pump power of 19 mW and the bias voltage of 30 V, a photoconductive antenna based on the optimized $\{$LT-GaAs/GaAs:Si$\}$ (111)A structure emits THz pulses with the average power of 2.3 $\mu$W at the pulse repetition frequency of 80 MHz; the conversion efficiency is 1.2 $\times$ 10$^{-4}$. It is shown that the dependence of the integral power of THz pulses of the antenna based on the $\{$LT-GaAs/GaAs:Si$\}$ (111)A structure on the applied voltage is superlinear; the dependence of this parameter on the optical pump power is plotted as a curve with saturation. It is shown that the designed antennas have a practical application in THz spectroscopy of biological solutions.