Terahertz time-domain spectroscopy is a widely used spectrum measurement technology in terahertz frequency domain, which can be applied to the spectrum analysis of many substances, and has an incomparable role in the research of chemistry, semiconductor and biomolecule. However, the consumption of the sample is more, and the occupied space of the whole system is larger in the terahertz time-domain spectroscopy system. These limitations hinder the further development of this system. In order to overcome the limitations of the system, a terahertz on-chip system, which integrates THz generating device, detecting device and waveguide transmission device on a silicon wafer, is designed. Due to the high integration of this system and the limitation of low-temperature gallium arsenide (LT-GaAs) of photoconductive antenna growth conditions, how to fabricate the LT-GaAs semiconductor film substrate and transfer and bond it is a key step in the THz on-chip system. The epitaxial wafer consists of semi-insulating gallium arsenide, GaAs buffer layer, AlAs sacrificial layer and LT-GaAs layer. In order to obtain LT-GaAs thin film with a thickness of 2 μm more efficiently, the selective corrosion rate of HCl solution at different temperatures and different concentrations with AlAs sacrificial layer is studied. The optimum volume ratio, concentration and optimum temperature of HCl during the preparation of LT-GaAs thin film are 13.57% and 73 ℃. Compared with the existing processes, this method has higher safety performance and lower equipment requirements. Finally, the single-layer LT-GaAs thin film is transferred and bonded to a silicon wafer. Terahertz signals generated by excitation of the photoconductive antenna structure using a femtosecond laser pulse are detected, and the experiment shows that the LT-GaAs film acquisition and transfer bonding process satisfies the production requirements of the THz on-chip system and has laid a solid foundation for the development of the THz on-chip system.