基于表面等离子体共振增强的硅基锗金属-半导体-金属光电探测器的设计研究

金属-半导体-金属光电探测器的光栅结构可激发表面等离子体, 有效增强探测器的吸收. 为深入研究器件结构对于表面等离子体的激发及共振增强的影响, 本文提出了一种具有超薄有源层的硅基锗金属-半导体-金属光电探测器的设计方法. 采用时域有限差分的方法详细分析了光栅周期、光栅厚度、 光栅间距及有源层厚度对于表面等离子体共振增强器件性能的影响, 通过仿真模拟获得了器件的最佳结构, 详细地分析了各个界面激发的表面等离子体及其共振模式对于光谱吸收增强的机理. 仿真结果表明, 有源层锗的厚度为400nm的超薄器件在通信波段具有较高的吸收, 尤其在1550nm波长处器件的归一化的光谱吸收率可以高达53.77%, 增强因子达7.22倍. 利用共振效应能够极大地提高高速器件的光电响应, 为解决光电探测器响应度与响应速度之间的相互制约关系提供了有效途径. 关键词： 表面等离子体 锗探测器 时域有限差分仿真

Design of silicon based germanium metal-semiconductor-metal photodetector enhanced by surface plasmon resonance

Surface plasmon excited by metallic grating integrated on metal-semiconductor-metal can greatly improve the absorption of devices. In order to deeply explore the excitation and resonant discipline of surface plasmon, a design of metal-semiconductor-metal based on ultra-thin germanium is proposed. By using finite difference time domain (FDTD) method, the effects of grating period, grating depth, grating space, and thickness of the active layer on the performance of surface plasmon resonance supported device are investigated in detail. The structure parameters of the device are optimized, and the mechanism of surface plasmon excited by each interface as well as spectrum absorption enhanced by surface plasmon resonance is analyzed in detail. Simulation results show that the germanium device with an ultra-thin active layer of 400 nm has a high absorption in the communication band, especially at the wavelength of 1550 nm the normalized spectral absorption can be as high as 53.77% with an enhancement factor of 7.22. Surface plasmon resonance can greatly improve the optical response of high-speed optoelectronic device, thus an efficient way is provided to solve the trade-off between photodetector responsivity and speed of the device.
Keywords： surface plasmon germanium photodetector finite difference time domain (FDTD) simulation