键合制备高质量Ge/Si异质结材料及高性能PIN光电探测器研究

构建高速低功耗的光通信网络已成为国家科技发展规划的布局重点之一。由于在Si上外延Ge薄膜时，会引入高密度的穿透位错，严重影响Ge/Si探测器性能。本项目创新采用非晶、多晶态Si或Ge过渡层低温键合技术和智能剥离技术在Si基上获得近体Ge质量的薄膜材料；研究键合中Ge/Si键合界面的应力分布、原子迁移、结构相变等关联性，分析位错的动力学机制，为抑制键合Ge薄膜中的位错成核和传播提供理论指导；创新采用高深宽比的图形化衬底创造应力弛豫条件，从根本上消除晶格失配和位错来源，制备穿透位错密度低于104 cm-2的Si基Ge薄膜材料；创新采用在Ge上溅射a-Si薄层后进行磷（P）旋涂掺杂，有效地抑制P在Ge中的扩散，实现高掺杂N型Ge浅结的制备。在此基础上研制出暗电流密度低于0.5 mA/cm2、1.55 μm波长下的响应度高于0.5 A/W、工作频率高于25 GHz的高性能Ge/Si PIN探测器。

Construction of high-speed and low-power optical communication network has became one important part in the layout of the national science and technology development plan. Due to the fact that high-density threading dislocations form in the Si-based epitaxial Ge film, the performance of the epitaxial Ge/Si photodetector significantly deteriorates. The low-temperature Ge/Si wafer bonding based on the amorphous Ge and Si or polycrystalline Ge and Si transition layer and the Smart-Cut technique are innovatively proposed in this project to fabricate the Si-based Ge film whose crystalline quality is close to that of bulk Ge. The relationship among the strain distribution, atom migration, and structural phase transition at Ge/Si bonded interface during Ge/Si wafer bonding is also investigated. Analysis of the dynamic mechanisms of dislocations, providing the theoretical guidance for the suppression of dislocation nucleation and diffusion in the wafer-bonded Ge film. The graphical substrate with high depth-to-width ratio is innovatively proposed to create the stress relaxation condition, eliminating the lattice mismatch and the source of dislocations fundamentally and fabricating the Si-based Ge film with threading dislocation density of 104 cm-2. The method that sputtering an a-Si layer on Ge wafer surface before the spin-doping of P source is proposed to restrain the diffusion of P atom in Ge, leading to the fo rmation of highly-doped N-type Ge shallow junction. Based on the descriptions above, the wafer-bonded Ge/Si PIN photodetector with dark current density of <0.5 mA/cm2, responsivity of >0.5 A/W at 1.55 μm, and 3dB-bandwidth of 25 GHz is fabricated.