Research On High-speed And High-efficiency MSM Silicon-based Photodetector Based On Light-trapping Structure

Facing the explosive growth of traffic load today,we need an electronic device that can handle a higher amount of data and has a higher bandwidth,and it needs to reduce costs and improve performance.The near-infrared band(800?950nm)is an important band for data communication.The preparation of photodetectors with high response speed and high quantum efficiency in this band is the demand for the development of optical communication technology and the realization of silicon-based optoelectronic integration^[1].However,the traditional silicon-based photodiode has a low absorption coefficient in the near-infrared wavelength range.To obtain higher quantum efficiency,it is necessary to increase the thickness of the absorption layer,which will increase the transmission time of photogenerated carriers and limit the data transmission rate.It is difficult to meet the requirement for high speed and high efficiency at the same time.Therefore,it is necessary to improve the responsivity of the intrinsic layer without increasing the thickness.Matlab simulation results show the3d B bandwidth can reach 25GB/s.This paper studies a high-speed and high-efficiency silicon-based MSM photodiode with surface micro-nano hole structures,which is fully compatible with CMOS integrated circuits.The device reduces the cost of manufacturing and packaging,and can realize the overall integration of monolithic optical modules in the future.In the design process,the FDTD finite element simulation software was used to simulate and design a variety of different micro-nano structures,and the calculation and analysis of absorption efficiency were carried out.The parameters of the micro-nano structure that affect the absorption were compared,and the optimized paramaters that maximized the quantum efficiency was found.With a Si thickness of 1.5?m,the absorption efficiency at the wavelength of 850nm reaches 58%.On this basis,the propagation mode of light inside the absorption layer was analyzed,and then the electric field distribution of a single electric light source propagating inside the device was simulated with FDTD software.Finally,TCAD simulation software was used to analyze the internal electric field of the MSM structure under the applied bias voltage.At the same time,the layout design and device processing were carried out,the layout design process was analyzed using L-Edit software,the device layout for the manufacturing process was designed,and several surface micro-nano light-trapped holes based MSM photodetector were developed.The spectral response test system was used to test its responsivity,quantum efficiency and dark current performance,and calculated the response bandwidth of the detector.Test results show the responsivity at850nm is 0.42A/W,the corresponding external quantum efficiency is 61%.