Sensitivity enhancement of SPR biosensor employing heterostructure blue phosphorus/MoS₂ and silicon layer

The present study proposes three new Kretschmann-configuration-based heterostructure surface plasmon resonance (SPR) sensors for biomolecule detection. The thicknesses of silver (Ag), silicon (Si) and heterostructure blue phosphorus (BlueP)/molybdenum disulfide (MoS₂) layers were optimized under the consideration of less reflectivity, full width at half maximum and enhanced sensitivity. After thickness optimization, the performance parameters of the proposed SPR sensor were also calculated in terms of sensitivity, quality factor and detection accuracy. The effect of increasing the number of heterostructure BlueP/molybdenum disulfide layers on the performance was also analyzed. It was also observed that the silicon layer played an important role in enhancing all performance parameters when it was deposited between the silver and heterostructure BlueP/molybdenum disulfide layers. The optimized sensitivity at a wavelength of 633 nm of the heterostructure BlueP/molybdenum disulfide monolayer and silicon layer was 282°/refractive index unit (RIU). The highest optimized sensitivity of 328°/RIU was achieved with two layers of heterostructure BlueP/molybdenum disulfide with a silicon layer thickness of 5 nm. It was found that the sensitivity increased by 16% when the number of heterostructure layers was changed. Other important parameters such as detection accuracy, quality factor and full width at half maximum were also calculated for the proposed SPR sensor. Moreover, a transverse magnetic field plot was created and a penetration depth of 138.25 nm for the proposed SPR sensor was calculated.