硅基长波长光电集成接收机的关键技术及相关理论研究

Electrical interconnection is not fast enough to satisfy the bandwidth demand for short distance communication with continuous increase in data traffic, so it has been a inevitable trend that optical interconnection supplants electrical interconnection. Silicon-based optoelectronic integration technology has been a research focus in recent 10 years for it could dramatically reduce the cost of optical interconnection. Due to the material properties of silicon, the long-wavelength photodetector can not be realized in standard CMOS process. Moreover, the cooperative design and integration between photodetector and the front-end circuits of optical receiver is not completely solved. The realization of long-wavelength optical receiver based on standard silicon process is still a challenging problem. Considering the current issues of silicon-based optoelectronic integrated receiver and our foundation in this field, the research on the key technologies and theories of silicon-based long-wavelength optical receiver is proposed in this project. The main contents are as following: 1 The relationship between build-in electric field of gemanium intrinsic region and implanted dopant distribution in P-type/N-type regions will be studied, and the coupling mechanism between gemanium detector and silicon-based waveguide will be analysed. Furthermore, the ultrafast transport mechanism for photo-generated carriers will be modelled, and a SOI-based germanium waveguide-integrated detector with complete response under the condition of 0V bias will be designed and fabricated. 2 The theories and methods of reducing the circuit noise and extending the operation frequency for the front-end circuit of optoelectronic integrated receiver will be expored. 3 The methods for cooperative design and integration between the detector and the front-end cirucuit will be studied, and a high performance optoelectronic integrated receiver responsed for long-length light (1550nm) will be realized. The research of this project is expected to achieve progress on SOI-based germanium waveguide-integrated detector and long-length optical receiver, and provide a useful reference for the realization of large-scale optoelectronic intregrated circuits.

在短距离通信中，电互连已无法满足系统对带宽的要求，光互连取代电互连已成为必然趋势。硅基光电子技术可有效降低光传输的成本，实现短距离光通信，因而一直是光电集成领域的研究热点。然而受硅材料特性的限制，标准CMOS工艺无法实现长波长光探测，且探测器与接收机前端电路的协同设计和集成尚未得到彻底解决。针对限制硅基长波长光电集成接收机发展的关键科学问题，本项目拟开展以下研究：1、研究硅基锗探测器的浅结掺杂注入分布与内建电场的关系，研究锗探测器与硅基光波导的耦合作用机理和光生载流子的超快输运模型，研制零偏压完全响应的SOI基锗波导探测器；2、研究降低光接收机前端电路噪声，扩展工作带宽的相关理论和方法；3、研究探测器和接收机前端电路的协同设计与集成，实现长波长响应的硅基光电集成接收机。本项目的研究有望在SOI基锗波导探测器及其光电集成接收机方面取得进展，为硅基光电集成芯片的发展提供理论积累和技术解决方案。

随着物联网、云计算及移动互联网等大数据载体的崛起，信息传输量雪崩式地增长，使得电路板间、芯片间以及芯片内部的信息通信对带宽提出更高的要求。然而受“电子瓶颈”的限制，传统的铜互连难以满足要求，故光互连取代电互连已成为必然趋势。硅基光电子技术可有效降低光传输成本，实现短距离光通信，因而成为光电集成领域的研究热点。项目围绕Ge波导探测器、光接收机前端电路，以及探测器与前端电路的协同设计与集成技术展开研究。主要研究成果包括：采用磷表面旋涂掺杂技术实现了Ge材料的N型高掺杂，与Al电极实现有效的欧姆接触。基于UHV-CVD外延生长出表面平整、结晶质量优良的Ge单晶薄膜，研制出零偏压完全响应的SOI基Ge波导探测器。研究了最佳偏置网络、T型匹配网络、L型匹配网络、π型匹配网络、并联双反馈、容性退化技术对电路带宽扩展的影响。提出一种交叉耦合的拓扑结构，通过提升辅助放大器的增益来降低跨阻放大器的等效输入噪声。利用串联电感π型网络和Gm提升技术，设计了前均衡电路。基于器件物理模型，建立了波导探测器的等效电路模型，实现了集成电路设计环境下的协同设计与仿真。基于UMC CMOS工艺研制出一款包括探测器电容、改进型RGC跨阻放大器、单转差放大器和输出缓冲级的光接收机前端电路，获得了61dBΩ的增益，8.1GHz的带宽，成功实现了12.5GHz的传输。基于IBM SiGe BiCMOS工艺，研制了一款跨阻增益为61dBΩ，-3dB带宽达15GHz的前端电路。提出了一种引入a-Ge中间层来实现Ge波导探测器和Si基接收机芯片的低温异质键合新方法。项目研究成果为硅基光电集成芯片的发展提供理论积累和技术解决方案。在国内外学术刊物发表论文22篇，其中SCI收录/EI收录20篇，核心期刊2篇，授权发明专利4项,申请发明专利12项。