Sensors and Devices Center, Bruno Kessler Foundation, I-38123 Trento, Italy.
Faculty of Science and Technology, Free University of Bozen, 39100 Bolzano, Italy.
Sensors (Basel). 2023 Jan 11;23(2):856. doi: 10.3390/s23020856.
Recent years have witnessed a growing interest in detectors capable of detecting single photons in the near-infrared (NIR), mainly due to the emergence of new applications such as light detection and ranging (LiDAR) for, e.g., autonomous driving. A silicon single-photon avalanche diode is surely one of the most interesting and available technologies, although it yields a low efficiency due to the low absorption coefficient of Si in the NIR. Here, we aim at overcoming this limitation through the integration of complementary metal-oxide-semiconductor (CMOS) -compatible nanostructures on silicon photodetectors. Specifically, we utilize silver grating arrays supporting surface plasmons polaritons (SPPs) to superficially confine the incoming NIR photons and therefore to increase the probability of photons generating an electron-hole pair. First, the plasmonic silver array is geometrically designed using time domain simulation software to achieve maximum detector performance at 950 nm. Then, a plasmonic silver array characterized by a pitch of 535 nm, a dot width of 428 nm, and a metal thickness of 110 nm is integrated by means of the focused ion beam technique on the detector. Finally, the integrated detector is electro-optically characterized, demonstrating a QE of 13% at 950 nm, 2.2 times higher than the reference. This result suggests the realization of a silicon device capable of detecting single NIR photons, at a low cost and with compatibility with standard CMOS technology platforms.
近年来，人们对能够探测近红外（NIR）单光子的探测器越来越感兴趣，这主要是由于新的应用的出现，例如用于自动驾驶的光探测和测距（LiDAR）。硅单光子雪崩二极管无疑是最有趣和可用的技术之一，尽管由于 Si 在 NIR 中的低吸收系数，其效率较低。在这里，我们旨在通过在硅光电探测器上集成互补金属氧化物半导体（CMOS）兼容的纳米结构来克服这一限制。具体来说，我们利用支持表面等离激元极化激元（SPP）的银光栅阵列来表面限制入射的近红外光子，从而增加光子产生电子-空穴对的概率。首先，使用时域仿真软件对等离子体银阵列进行几何设计，以在 950nm 处实现最大的探测器性能。然后，通过聚焦离子束技术将具有 535nm 节距、428nm 点宽和 110nm 金属厚度的等离子体银阵列集成到探测器上。最后，对集成探测器进行电光特性表征，在 950nm 处的 QE 为 13%，比参考值高 2.2 倍。这一结果表明，实现了一种能够探测单个近红外光子的硅器件，成本低，与标准 CMOS 技术平台兼容。
