Platinum Layers Sandwiched Between Black Phosphorous and Graphene for Enhanced SPR Sensor Performance

Maheswari Pandaram,Ravi Veeran,Rajan Jha,Zbigniew Jaroszewicz,Rajesh Karuppaiya Balasundaram,Subanya Santhanakumar

doi:10.1007/s11468-021-01507-5

Abstract

Highly sensitive surface plasmon resonance (SPR) sensor consisting of Ag-Pt bimetallic films sandwiched with 2D materials black phosphorus (BP) and graphene over Pt layer in Kretschmann configuration is analyzed theoretically using the transfer matrix method. Numerical results show that upon suitable optimization of thickness of Ag-Pt layers and the number of layers of BP and graphene, sensitivity as high as 412°/RIU (degree/refractive index unit) can be achieved for p-polarized light of wavelength 633 nm. This performance can be tuned and controlled by changing the number of layers of BP and graphene. Furthermore, the addition of graphene and heterostructures of black phosphorus not only improved the sensitivity of the sensor but also kept the FWHM of the resonance curve much smaller than the conventional sensor utilizing Au as plasmonic metal and hence improved the resolution to a significant extent. We expect that this new proposed design will be useful for medical diagnosis, biomolecular detection, and chemical examination.

Highlights

Surface Plasmon resonance (SPR) is the one of the most powerful optical techniques used for medical diagnostics, enzyme and gaseous detection, food safety[1,2,3,4,5,6,7,8]
Srivastava et al reported that implementation of double layer Black Phosphorus (BP) enhanced the sensitivity by 35%[27].Recently, Graphene on the other hand exhibits remarkable properties such ashigh charge carrier mobility which inducestrong coupling at the interface between metal-graphene films [28].Wu et al reported utilizing a graphene enhance the sensitivity by 25% compared with conventional goldbased SPR sensor[29]
The conditionof minimum reflectance(Rmin)close to zero ensures coupling of maximum energy of incident TM polarized light with the surface plasmon and it is necessary for the design of any SPR sensor to have improvised sensitivity and resolution[40,41,42]

Summary

Introduction

SPR is the one of the most powerful optical techniques used for medical diagnostics, enzyme and gaseous detection, food safety[1,2,3,4,5,6,7,8]. Shukla et al theoretically analyzed the performance of the SPR sensor with Platinum layer coated on optical fiber They observed that the sensitivity of the sensor enhances linearly with the increase in the refractive index of the sensing medium for all thickness of platinum layer and for a given refractive index of the sensing medium [20].Recently,Black Phosphorus (BP) is identified as one the of potential 2D material [21] which gains rapid attention due to its widely tunable and direct bad gap, remarkable electrical and optical properties and higher carrier mobility [22,23,24,25]. It is noted that the proposed sensing configuration enhancessensitivity but still keep the FWHM of the resonance curve much smaller than the conventional sensor utilizing Au as plasmonic material and improved the resolution to a greater extend. The top surface graphene coat protect the metal surface but improved the biomolecular absorption through high surface to volume ratio and Pi conjugation structure

Theory

3.Results and Discussions

Conclusion