Low temperature grown GaAs (LT-GaAs) has become the choice material for THz photoconductive antennas (PCA) designed for 800 nm applications. Its ultrafast response, high carrier mobility, and high resistivity make it ideal for THz applications. Motivated by the possibility of widening the detection bandwidth and reducing production cost, we explore the use of LT-GaAs grown on Silicon substrates as a material for THz PCAs . Silicon is less absorbing in the THz region compared to GaAs, and can thus reduce THz absorption by the substrate material. Growing GaAs on Si substrates is difficult. Often the GaAs layers grown are riddled with defects such as dislocations, anti-phase boundaries, among others . However, for THz applications, the photoconductive material does not have to be pristine. In this work, optical pump terahertz probe technique was used to measure the complex conductivities of LT-GaAs-on-Si to understand its conduction mechanism and ultimately its suitability as photoconductive material.
© 2019 Japan Society of Applied Physics, The Optical Society (OSA)PDF Article