吸收倍增分离型波导Si/Ge雪崩探测器件的研究

The new generation of information technology will develop in the direction of high speed transmission of large volumes of information, such as Tpbs data transfer. Therefore, the separated-absorption-multiplication (SAM) waveguide Si/Ge avalanche photodetectors (APD) with low excess noise, high response and high bandwidth, will be the core device for the development of the optoelectronic integrated chip. However, the thickness mismatching between silicon-material of the traditional Si/Ge SAM-APD devices and the single-mode silicon waveguide makes it become the key problem for high performance waveguide Si/Ge SAM-APD, with high-efficiency light coupling and carrier multiplication. In this project, a new structure of the waveguide Si/Ge SAM-APD devices will be designed and fabricated, with a nano-scale germanium absorption layer and a single-side silicon multiplication region in the silicon waveguide layer. The Light will be coupled from Si single-mode waveguides by evanescent wave and absorbed by Ge absorption layer, and the multiplication region is located in the waveguide layer. The directions of the electric fields in absorption layer and multiplication region are orthogonal. The design of device will eliminate the contradiction of the structure requirements for high responsivity and high multiplication. The quality of the crystal lattice will be better, the cross-sectional area of the heterojunction will be smaller, the transit time of the carriers will be shorter and the excess noise will be lower for the new structure device. Therefore, based on the selective epitaxial growth of high quality single crystals of nano-scale Ge by UHV-CVD，high performance waveguide avalanche photodetector could be fabricated with responsivity of over 0.80A/W, sensitivity of above -35dBm and gain bandwidth product of over 350GHz.

新一代信息技术将向着Tbps的高速度大容量数据传输方向发展，具有低过剩噪声、高灵敏度和大带宽优势的吸收倍增分离型（SAM）波导Si/Ge雪崩探测器将是未来光电集成芯片发展的核心器件。但是Si/Ge SAM-APD器件和集成芯片光通道对Si材料厚度要求的不匹配，使得同时实现高效载流子倍增和高效光耦合，成为了该波导器件研究的关键。本项目提出了纳米Ge纵向吸收、Si波导层横向单侧倍增的波导Si/Ge SAM-APD结构，光从Si单模波导通过倏逝波耦合到Ge吸收层，倍增区位于横向波导层中，光吸收和载流子倍增方向互相垂直，解除高响应度和高增益性能对器件结构要求的相互制约，更有利于获得高的外延晶格质量，小的异质结截面积，短的载流子渡越时间和低的过剩噪声性能，基于UHV-CVD选择外延方法，能够制备出高性能的波导雪崩器件，响应度大于0.80A/W，灵敏度高于-35dBm，增益带宽积大于350GHz。

新一代信息技术将向着Tbps的高速度大容量数据传输方向发展，具有低过剩噪声、高灵敏度和大带宽优势的吸收倍增分离型（SAM）波导Si/Ge雪崩探测器将是未来光电集成芯片发展的核心器件。但是Si/Ge SAM-APD器件和集成芯片光通道对Si材料厚度要求的不匹配，使得同时实现高效载流子倍增和高效光耦合，成为了该波导器件研究的关键。本项目研究了纳米Ge纵向吸收、Si波导层横向单侧倍增的波导Si/Ge SAM-APD结构，理论验证了此结构能够解除高响应度和高增益性能对雪崩器件结构要求的相互制约，基于UHV-CVD选择外延方法实验论证了此结构能够获得高的外延晶格质量，小的异质结截面积，短的载流子渡越时间和低的过剩噪声性能，理论上器件的光吸收效率达到90%，对应的响应度>1.1A/W，倍增系数>800，器件带宽大于>45GHz，倍增区宽度为400nm时增益带宽积限制在>190GHz，此结果受到离散模型自身限制。