The much thicker intrinsic absorption layer (IAL) in normal-incidence Ge-on-Si photodetectors (NIPD) usually causes a contradiction between responsivity and bandwidth. In response to this issue, here, we simulate the design of an NIPD with geranium (Ge) layers based on a “fishnet” metasurface, leading to a reduced device thickness as thin as 380$$nm. The optical simulation results show that the light field can be perfectly localized in the 210$$nm IAL, and the absorptivity is as high as 99.45% at 1550$$nm, which is even better than bulk materials. Moreover, the electrical simulation results suggest that the horizontal size of the photosensitive region can be reduced to 11.2 $\mu$m, while the responsivity of the photodetector is close to 1 A/W at −1$$V bias voltage, which is nearly 23 times that of a bulk device with the same thickness, and the 3dB bandwidth is up to 40$$GHz, which can be compared with waveguide photodetectors. Besides, this device also demonstrates a high signal-to-noise ratio with a low dark current of 28.68 nA, making it an excellent PD for opto-electrical communication.

正入射硅基硅光电探测器 (NIPD) 中较厚的本征吸收层 (IAL) 通常会导致响应度和带宽之间的矛盾。针对这个问题，我们在这里模拟了基于“鱼网”超表面的天竺葵（Ge）层NIPD的设计，从而使设备厚度减少至380$$纳米。光学模拟结果表明，光场可以完美定位在210°$$nm IAL，1550 时吸收率高达 99.45%$$nm，甚至比块体材料更好。此外，电学模拟结果表明，光敏区域的水平尺寸可以减小到11.2$\mu$m，而光电探测器的响应度在 -1 时接近 1 A/W$$V偏置电压，是同厚度体器件的近23倍，3dB带宽高达40$$GHz，可以与波导光电探测器进行比较。此外，该器件还具有高信噪比和 28.68 nA 的低暗电流，使其成为光电通信的优秀 PD。