Department of Electrical and Electronics Engineering, Bilkent University, Ankara 06800, Turkey.
UNAM-National Nanotechnology Research Center, Bilkent University, Ankara 06800, Turkey.
Sci Rep. 2017 Feb 9;7:42349. doi: 10.1038/srep42349.
Plasmonically enhanced metal-insulator-metal (MIM) type structures are popular among perfect absorbers and photodetectors in which the field enhancement (for increased absorption) mechanism is directly coupled with collection (photocurrent) processes. In this work we propose a device structure that decouples absorption and collection parts for independent optimization. Double-stacked MIM (i.e. MIMIM) photodetectors operating in the near-infrared (NIR) spectrum up to 1200 nm wavelength are demonstrated. In the absorbing MIM (at the top side), we have used Silver nanoparticles resulting from dewetting, yielding a very low reflection of 10% for the most part of the 400 to 1000 nm wavelength range. An unconventional plasmonic material, Chromium, exhibits an absorption peak of over 80% at 1000 nm. The complete device has been fabricated and the photo-collection tunneling MIM (at the bottom) suppresses the leakage current by metal workfunction difference. An optimized stack consisting of Silver - Hafnium Oxide - Chromium - Aluminum Oxide - Silver nanoparticles (from bottom to top) yields a dark current of 7 nA and a photoresponsivity peak of 0.962 mA/W at 1000 nm and a full width at half maximum of 300 nm, while applied bias is 50 mV and device areas are 300 μm × 600 μm.
等离子增强金属-绝缘体-金属（MIM）型结构在完美吸收体和光电探测器中很受欢迎，其中场增强（用于增加吸收）机制直接与收集（光电流）过程耦合。在这项工作中，我们提出了一种器件结构，将吸收和收集部分解耦，以便进行独立优化。演示了工作在近红外（NIR）光谱中、波长高达 1200nm 的双层 MIM（即 MIMIM）光电探测器。在吸收 MIM（在顶部）中，我们使用了由去湿形成的银纳米颗粒，在 400 到 1000nm 波长范围内，大部分的反射率非常低，只有 10%。一种非传统的等离子体材料——铬，在 1000nm 处表现出超过 80%的吸收峰。整个器件已经制造完成，光电收集隧道 MIM（在底部）通过金属功函数差抑制漏电流。由银-氧化铪-铬-氧化铝-银纳米颗粒（从下到上）组成的优化堆叠在 1000nm 时产生 7nA 的暗电流和 0.962mA/W 的光响应度峰值，半峰全宽为 300nm，而外加偏压为 50mV，器件面积为 300μm×600μm。
