Qi Zhiyang, Zhai Yusheng, Wen Long, Wang Qilong, Chen Qin, Iqbal Sami, Chen Guangdian, Xu Ji, Tu Yan
Joint International Research Laboratory of Information Display and Visualization, School of Electronic Science and Engineering, Southeast University, Nanjing 210096, People's Republic of China.
Nanotechnology. 2017 May 22;28(27):275202. doi: 10.1088/1361-6528/aa74a3.
The heterojunction between metal and silicon (Si) is an attractive route to extend the response of Si-based photodiodes into the near-infrared (NIR) region, so-called Schottky barrier diodes. Photons absorbed into a metallic nanostructure excite the surface plasmon resonances (SPRs), which can be damped non-radiatively through the creation of hot electrons. Unfortunately, the quantum efficiency of hot electron detectors remains low due to low optical absorption and poor electron injection efficiency. In this study, we propose an efficient and low-cost plasmonic hot electron NIR photodetector based on a Au nanoparticle (Au NP)-decorated Si pyramid Schottky junction. The large-area and lithography-free photodetector is realized by using an anisotropic chemical wet etching and rapid thermal annealing (RTA) of a thin Au film. We experimentally demonstrate that these hot electron detectors have broad photoresponsivity spectra in the NIR region of 1200-1475 nm, with a low dark current on the order of 10 A cm. The observed responsivities enable these devices to be competitive with other reported Si-based NIR hot electron photodetectors using perfectly periodic nanostructures. The improved performance is attributed to the pyramid surface which can enhance light trapping and the localized electric field, and the nano-sized Au NPs which are beneficial for the tunneling of hot electrons. The simple and large-area preparation processes make them suitable for large-scale thermophotovoltaic cell and low-cost NIR detection applications.
金属与硅（Si）之间的异质结是将硅基光电二极管的响应扩展到近红外（NIR）区域的一种有吸引力的途径，即所谓的肖特基势垒二极管。吸收到金属纳米结构中的光子会激发表面等离子体共振（SPR），而SPR可以通过产生热电子以非辐射方式被衰减。不幸的是，由于光吸收低和电子注入效率差，热电子探测器的量子效率仍然很低。在本研究中，我们提出了一种基于金纳米颗粒（Au NP）修饰的硅金字塔肖特基结的高效低成本等离子体热电子近红外光电探测器。通过对薄金膜进行各向异性化学湿法蚀刻和快速热退火（RTA），实现了大面积且无需光刻的光电探测器。我们通过实验证明，这些热电子探测器在1200 - 1475 nm的近红外区域具有宽光响应光谱，暗电流低至10 A cm量级。观察到的响应度使这些器件能够与其他报道的使用完美周期性纳米结构的硅基近红外热电子光电探测器相竞争。性能的提升归因于金字塔表面能够增强光捕获和局部电场，以及纳米尺寸的金纳米颗粒有利于热电子的隧穿。简单的大面积制备工艺使其适用于大规模热光伏电池和低成本近红外检测应用。
