Characterisation and Modeling of Terahertz Field Generation of Photoconductive Antennas Based on Semi Insulating and Low Temperature Grown GaAs

The properties of terahertz emission has been investigated from photoconductive switches based GaAs, gated by a femtosecond laser. The emission properties of photoconductive antenna (PCA) based on low-temperature-grown (LTG) GaAs has been studied and compared with those of semi-insulating (SI) GaAs PCAs. In such GaAs materials presence of the charged defects 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. In this work we demonstrate that carrier lifetime affects the transient response of the antenna, and the mobility of electrons (and holes) affects the power of radiation. LTG-GaAs with lower carrier lifetime is more appropriate than SI-GaAs for high frequency applications, and SI-GaAs with higher mobility has better results in high power applications. Furthermore, the design of contacts investigated to achieve better directivity and gain of photoconductive antennas

Keywords:

Photoconductive antenna (PCA) , LTG-GaAs , SI-GaAs , THz radiation , Femtosecond laser