Zhang Zhifang, Yan Jia, You Jie, Zhu Yanyan, Wang Liming, Zhong Zhenyang, Jiang Zuimin
State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200438, People's Republic of China.
Wide Bandgap Semiconductor Technology Disciplines State Key Laboratory, School of Microelectronics, Xidian University, Xi'an 710071, People's Republic of China.
Nanotechnology. 2024 Jul 22;35(40). doi: 10.1088/1361-6528/ad61f1.
Although the photoresponse cut-off wavelength of Si is about 1100 nm due to the Si bandgap energy, the internal photoemission effect (IPE) of the Au/Si junction in Schottky detector can extend the absorption wavelength, which makes it a promising candidate for the Si-based infrared detector. However, due to low light absorption, low photon-electron interaction, and poor electron injection efficiency, the near-infrared light detection efficiency of the Schottky detector is still insufficient. The synergistic effect of Si nano/microstructures with a strong light trapping effect and nanoscale Au films with surface plasmon enhanced absorption may provide an effective solution for improving the detection efficiency. In this paper, a large-area periodic Si microcone array covered by an Au film has successfully been fabricated by one-time dry etching based on the mature polystyrene microspheres lithography technique and vacuum thermal deposition, and its properties for hot electron-based near infrared photodetection are investigated. Optical measurements show that the 20 nm-thick Au covered Si microcone array exhibits a low reflectance and a strong absorption (about 85%) in wide wavelength range (900-2500 nm), and the detection responsivity can reach a value as high as 17.1 and 7.0 mA Wat 1200 and 1310 nm under the front illumination, and 35.9 mA Wat 1310 nm under the back illumination respectively. Three-dimensional finite difference time domain (3D-FDTD) simulation results show that the enhanced local electric field in the Au layer distributes near the air/Au interface under the front illumination and close to the Au/Si interface under the back illumination. The back illumination favors the injection of photo-generated hot electrons in Au layer into Si, which can explain the higher responsivity under the back illumination. Our research is expected to promote the practical application of Schottky photodetectors to Si-compatible near infrared photodetectors.
由于硅的带隙能量，硅的光响应截止波长约为1100 nm，然而肖特基探测器中Au/Si结的内光电发射效应（IPE）可以扩展吸收波长，这使其成为基于硅的红外探测器的一个有潜力的候选者。然而，由于光吸收低、光子 - 电子相互作用弱以及电子注入效率差，肖特基探测器的近红外光探测效率仍然不足。具有强光捕获效应的硅纳米/微结构与具有表面等离子体增强吸收的纳米级金膜的协同效应可能为提高探测效率提供有效解决方案。本文基于成熟的聚苯乙烯微球光刻技术和真空热沉积，通过一次性干法刻蚀成功制备了大面积周期性金膜覆盖的硅微锥阵列，并研究了其基于热电子的近红外光探测特性。光学测量表明，20 nm厚金膜覆盖的硅微锥阵列在宽波长范围（900 - 2500 nm）内表现出低反射率和强吸收（约85%），在前照光下，在1200和1310 nm处的探测响应率分别可达17.1和7.0 mA/W，在背照光下在1310 nm处可达35.9 mA/W。三维时域有限差分（3D - FDTD）模拟结果表明，前照光下金层中增强的局部电场分布在空气/金界面附近，背照光下靠近金/硅界面。背照光有利于光生热电子从金层注入硅中，这可以解释背照光下更高的响应率。我们的研究有望推动肖特基光电探测器在与硅兼容的近红外光电探测器中的实际应用。
Zotero 插件