Effects of microstructure of low temperature grown GaAs films on the properties of terahertz wave detection

Effects of microstructure of molecular beam epitaxially grown GaAs films at low temperature on the properties of terahertz detection have been investigated. Microstructural changes of the films before and after in-situ annealing strongly influence the terahertz wave SNRs in the receiver. The films grown at 150°C and in-situ annealed at 600°C showed a poly- crystalline state, and those grown at 250°C or higher temperature and in-situ annealed at 600°C revealed epitaxial GaAs layers including As-rich precipitates. The SNRs of the terahertz wave were measured to be 10 3 to 10 4 . The best value of the SNR 10 4 was obtained with the polycrystalline GaAs layer.