State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instruments, Tsinghua University, Beijing 100084, China.
College of Information and Control Engineering, China University of Petroleum (East China), Qingdao 266580, China.
Biosens Bioelectron. 2017 Dec 15;98:68-75. doi: 10.1016/j.bios.2017.06.027. Epub 2017 Jun 15.
The extraordinary properties of black phosphorus (BP) make it a promising candidate for next-generation transistor chemical sensors. However, BP films reported so far are supported on substrate, and substrate scattering drastically deteriorates its electrical properties. Consequentially, the potential sensing capability of intrinsic BP is highly underestimated and its sensing mechanism is masked. Additionally, the optimum sensing regime of BP remains unexplored. This article is the first demonstration of suspended BP sensor operated in subthreshold regime. BP exhibited significant enhancement of sensitivity for ultra-low-concentration mercury detection in the absence of substrate, and the sensitivity reached maximum in subthreshold regime. Without substrate scattering, the suspended BP device demonstrated 10 times lower 1/f noise which contributed to better signal-to-noise ratio. Therefore, rapid label-free trace detection of Hg was achieved with detection limit of 0.01 ppb, lower than the world health organization (WHO) tolerance level (1 ppb). The time constant for ion detection extracted was 3s. Additionally, experimental results revealed that good stability, repeatability, and selectivity were achieved. BP sensors also demonstrated the ability of detecting mercury ions in environment water samples. The underling sensing mechanism of intrinsic BP was ascribed to the carrier density variation resulted from surface charge gating effect, so suspended BP in subthreshold regime with optimum gating effect demonstrated the best sensitivity. Our results show the prominent advantages of intrinsic BP as a sensing material.
黑磷（BP）的非凡性质使其成为下一代晶体管化学传感器的有前途的候选者。然而，迄今为止报道的 BP 薄膜都需要支撑基底，而基底散射会严重恶化其电性能。因此，对本征 BP 的潜在传感能力的评估被大大低估了，其传感机制也被掩盖了。此外，BP 的最佳传感范围也尚未得到探索。本文首次展示了在亚阈值区工作的悬浮 BP 传感器。在没有基底的情况下，BP 对超低浓度汞的检测表现出了显著的灵敏度增强，并且在亚阈值区达到了最大灵敏度。由于没有基底散射，悬浮的 BP 器件的 1/f 噪声降低了 10 倍，从而提高了信噪比。因此，实现了快速无标记痕量 Hg 的检测，检测限达到 0.01 ppb，低于世界卫生组织（WHO）的耐受水平（1 ppb）。所提取的离子检测时间常数为 3s。此外，实验结果表明，实现了良好的稳定性、重复性和选择性。BP 传感器还展示了检测环境水样中汞离子的能力。本征 BP 的传感机制归因于表面电荷门控效应导致的载流子密度变化，因此在具有最佳门控效应的亚阈值区悬浮的 BP 表现出了最佳的灵敏度。我们的结果表明，本征 BP 作为传感材料具有突出的优势。
