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In this theoretical study, the effect of semiconductor on sensitivity of a graphene-based surface plasmon resonance (SPR) biosensor has been presented. Different semiconductors such as silicon (Si), germanium (Ge) and wurtzite III-V nitrides (AlN, GaN and InN) have been placed in between active silver (Ag) metal and graphene layer. Our simulation result shows that addition of semiconductor layer enhances the sensitivity by a factor of 3.76, 2.19, 3.82, 3.94 and 4.17 respectively for Si, Ge, InN, GaN and AlN. Also, we have examined the field enhancement factor due to above semiconductors and found maximum field intensity enhancement for the case of AlN. The analysis shows that best performance is achieved for red He-Ne laser light when optimized thicknesses of silver, AlN and graphene layer are 55, 14 and 0.34 nm (monolayer of graphene), respectively. More specifically, AlN would be a better choice for biosensing application in SPR biosensor.

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In this paper, we have studied theoretically the effect of bimetallic silver/ gold layer on sensitivity of the graphene based surface plasmon resonance (SPR) biosensor. Here, silver layer (instead of chromium and titanium) is used as an adhesive layer in between gold and BK7 glass prism. The optimized thickness of silver/gold layers reported in literature has been used for the analysis of various sensitivity parameters of the biosensor. A computational simulation is performed to analyze the nature of plasmon dip shift with respect to the addition of graphene layer and binding layer respectively.