Yuan Kaibo, Qian Qinqin, Wu Miaomiao, Wang Bingxia, Zeng Shuweng, Chen Dong, Birowosuto Muhammad Danang, Ang Diing Shenp, Gu Chenjie
The Research Institute of Advanced Technology, Ningbo University, Ningbo, Zhejiang 315211, China.
Ningbo Institute of Oceanography, Ningbo 315800, P. R. China.
Phys Chem Chem Phys. 2024 Apr 3;26(14):10814-10823. doi: 10.1039/d4cp00641k.
Active control of the surface-enhanced Raman scattering (SERS) enhancement shows great potential for realizing smart detection of different molecules. However, conventional methods usually involve time-consuming structural design or a sophisticated fabrication process. Herein, we reported an electrically tunable field effect transistor (FET) comprising a WO/MoO hybrid as the SERS active layer. In the experiment, WO/MoO hybrids were first prepared by mixing different molar ratios of WO and MoO oxides. Then, R6G molecules were used as Raman reporters, showing that the intensity of the SERS signal observed on the most optimal hybrids (molar ratio = 1 : 3) could be increased by two times as high as that observed on a single WO or MoO based substrate, which was ascribed to enhanced charge transfer efficiency by the constructed nano-heterojunction between the WO and MoO oxides. Thereafter, a back-gate FET was fabricated on a SiO/Si substrate, and the most optimal WO/MoO hybrid was deposited as the gate channel and the SERS active layer. After that, a series of gate biases (from -15 V to 15 V) were implemented to actively tune the SERS performance of the FET. It is evident that the SERS EF can be further tuned from 2.39 × 10 (-15 V) to 6.55 × 10 (+10 V), which is ∼7.4/4.1 times higher than that observed on the pure WO device (8.81 × 10) or pure MoO (1.61 × 10) device, respectively. Finally, the mechanism behind the electrical tuning strategy was investigated. It is revealed that a positive voltage would bend the conduction band down, which increased the electron density near the Fermi level. Consequently, it triggered the resonance charge transfer and significantly improved the SERS performance. In contrast, a negative gate voltage attracted the holes to the Fermi level, which deferred the charge transfer process, and caused the reduction of the SERS enhancement.
表面增强拉曼散射（SERS）增强的主动控制在实现不同分子的智能检测方面显示出巨大潜力。然而，传统方法通常涉及耗时的结构设计或复杂的制造过程。在此，我们报道了一种电可调场效应晶体管（FET），其包含WO/MoO混合物作为SERS活性层。在实验中，首先通过混合不同摩尔比的WO和MoO氧化物制备WO/MoO混合物。然后，使用R6G分子作为拉曼报告分子，结果表明在最优化的混合物（摩尔比 = 1 : 3）上观察到的SERS信号强度比在单一WO或MoO基衬底上观察到的信号强度高出两倍，这归因于WO和MoO氧化物之间构建的纳米异质结提高了电荷转移效率。此后，在SiO/Si衬底上制造了一个背栅FET，并沉积最优化的WO/MoO混合物作为栅极沟道和SERS活性层。之后，施加一系列栅极偏压（从 -15 V到15 V）以主动调节FET的SERS性能。显然，SERS增强因子（EF）可以进一步从2.39 × 10 （-15 V）调节到6.55 × 10 （+10 V），分别比在纯WO器件（8.81 × 10）或纯MoO（1.61 × 10）器件上观察到的高出约7.4/4.1倍。最后，研究了电调谐策略背后的机制。结果表明，正电压会使导带向下弯曲，从而增加费米能级附近的电子密度。因此，它引发了共振电荷转移并显著提高了SERS性能。相反，负栅极电压将空穴吸引到费米能级，这延迟了电荷转移过程，并导致SERS增强的降低。
