1.55µm光纤飞秒激光器辐照低温生长的InGaAs光电导天线能产生THz辐射，这可以极大地推动THz源向廉价、小型化和集成化方向发展，受到人们的重视。然而，低温生长的InGaAs光电导天线受材料较低电阻率和迁移率的限制，产生的辐射功率跟低温生长GaAs基光电导天线相比弱很多。这主要是由普通模式下低温生长InGaAs材料中过量As含量过少，导致退火后As沉淀很难形成及合金散射造成的。本项目拟采用短周期InAs/GaAs超晶格替代InGaAs，并结合分子束外延中的迁移增强和调制束外延技术来解决这一难题。InAs/GaAs短周期超晶格结构可抑制合金散射，提高迁移率。低温下新结构中GaAs层引入的过量As增加，退火后As沉淀易生成。此外，结合InAlAs陷阱层可进一步提高电阻率，为制备高性能，特别是高辐射功率THz天线奠定基础。本项目在医学成像、环境监测、卫星通信、军事等领域具有广泛的应用前景。

THz radiation can be generated by a 1.55μm femtosecond fiber laser illuminating a low-temperature-growth(LTG) InGaAs photoconductive antenna. It can greatly promote the development of low-cost, compact and integrated THz sources. Therefore, its development is receiving increasing attention. However, LTG InGaAs photoconductive antennas are limited by the lower resistivity and mobility of materials. The radiated power which is generated by LTG InGaAs is much weaker than the photoconductive antenna made of LTG GaAs-based material. The main reason for this is that the excessive As content in the low- temperature-growth InGaAs material by using the normal mode is too small, which results in the formation of As precipitates after annealing is very difficult. In addition, alloy scattering is also a main reason. In order to solve this problem, we are going to replace InGaAs with a short-period InAs/GaAs superlattice, and combine the special techniques in molecular beam epitaxy--migration enhanced epitaxy and modulated beam epitaxy in this project. The InAs/GaAs short-period superlattice structure can suppress alloy scattering and improve mobility. In the case of low temperature growth, the amount of excess As introduced by the GaAs layer in the new structure increases, and thus As precipitation is easily formed after annealing. In addition, the resistivity can be further increased by using the InAlAs trap layer. This lays the foundation for the fabrication of high performance, especially high radiated power THz antennas. The project has wide application prospects in medical imaging, environmental monitoring, satellite communications, military and other fields.