Sensitivity-enhanced surface plasmon sensor modified with MoSe₂ overlayer

In this work, a sensitivity-enhanced surface plasmon resonance (SPR) sensor, which is integrated with MoSe₂ as modification overlayer, is proposed and investigated. The sensor is constructed by physically depositing MoSe₂ onto the surface of a conventional SPR sensor based on Krestchman configuration. Thanks to the commendable properties of MoSe₂ including high carrier mobility, high refractive index (RI), large surface area, and so forth, adding an overlayer within a certain thickness can effectively improve the RI sensitivity. Experimental results show that, with the increased number of deposition cycles-which positively correlates with the duty ratio and the MoSe₂ overlayer's thickness-the sensitivity at first increases, and then declines. The highest sensitivity of 2524.8 nm/RIU is achieved experimentally, which corresponds to the 2 deposition cycles. This shows an improvement of 36.3%, compared with the case without the MoSe₂ modification. The ease of fabrication, efficiency of performance enhancement, and great potentials (such as the large surface area of MoSe₂ for linking abundant functional groups) allow the method presented in this paper to contribute to the development of performance-enhanced SPR sensors for the biological, chemical, and medical fields.