Pulsed photoconductive antenna terahertz sources made on ion-implanted GaAs substrates

In this work we show that improved performances of terahertz emitters can be obtained using an ion implantation process. Our photoconductive materials consist of high-resistivity GaAs substrates. Terahertz pulses are generated by exciting our devices with ultrashort near-infrared laser pulses. The ion implantation introduces non-radiative centres, which reduce the carrier lifetime in GaAs. The presence of the charged defects also induces a redistribution of the electric field between the antenna electrodes. This effect has a huge influence on the amplitude of the radiated terahertz field. Results obtained as a function of the laser excitation power are discussed and a comparison of the performance of these devices with a conventional antenna-type emitter is given.