Bi进入GaAs纳米线不仅能有效的调控其能带带隙向红外波段移动，并且会诱导形成新的晶体缺陷结构，可以用来调控其光学极化偏振方向。同时对Bi进入GaAs纳米线后形成的缺陷进行化学表征，可以为GaAsBi纳米线的优化生长提供理论依据。本项目主要解决以下问题：1）Bi掺入GaAs纳米线后其Bi组分和形成的缺陷结构对其能带结构和载流子复合效率的影响；2）Bi进入GaAs纳米线后形成的缺陷态和表面的缺陷态在载流子复合过程中将作为非辐射复合中心，如何对这些缺陷利用光探测磁共振技术进行化学表征；3）如何利用Bi进入GaAs纳米线后形成的晶体缺陷结构调控其发光偏振极化方向。这些问题的解决为未来在可能的红外纳米偏振光探测和光发射器件方面奠定研究基础。

Due to their unusual optical and electronic properties, semiconductor nanowire (NW) from III-V semiconductors structures， for example，GaAs NWs have attracted much attention as a building block for a new generation of electronic and optoelectronic devices such as nano-lasers, solar-cell and photodetectors for several decades. By incorporation Bi into GaAs NWs, the band gap can not only be tuned to the attractive optical fiber communication wavelength 1.3 μm (0.95 eV) and 1.55μm (0.80 eV), but also create new defect structure, which can be employed to control the degree of linear optical polarization. Meantime, chemical identification of the defect in Bi induced GaAs NWs would help optimize the growth of GaAsBI NWs. The objectives of this research program are the following: 1) How to probe the effect of Bi content and the formation of defect on the band structure and carrier relaxation of the single GaAsBi nanowire grown by Au-assisted MBE; 2)How to use optical detected magnetic resonance (ODMR) technique to identify of the involved point defects and surface defects which act as a dominant role in the non-radiative recombination process in GaAsBi NWs; 3)How to control optical polarization direction by use of the new crystal defect phase in GaAsBi NWs. This may prove useful in, for example, infrared NW laser, optically gated switches and highly dense optical interconnects in photonic-based circuits, where polarization of emission and detection could increase the information bandwidth.