Influence of ultrathin chromium adhesion layer on different metal thicknesses of SPR-based sensor using FDTD. (2019)

• Record Type: Journal Article
• Authors: Mohamad, Najmiah Radiah; Mei, Gan Siew; Jamil, Nur Akmar; Majlis, BurhanuddinYeop; Menon, P. Susthitha
• Is Part Of: Materials today. Volume 7:Part 2(2019)
• Page Start: 732
• Page End: 737
• Publication Date: 2019
• Subjects: Kretschmann -- gold -- silver -- copper -- thin film -- optical sensor -- FHWM -- sensitivity -- SPR; Materials science -- Congresses -- Periodicals; 620.1
• DOI: 10.1016/j.matpr.2018.12.068
• Languages: English
• ISSNs: 2214-7853

Abstract

Abstract: Chromium (Cr) layer with ultrathin thickness plays significant role as adhesion layer to attach the prism with various metallic materials in a Surface Plasmon Resonance (SPR) sensor. In this research, the presence of fixed 0.5nm Cr adhesion layer has been investigated to evaluate its influence to reflectivity, resonance angle (θRes ) and full-width at half maximum (FWHM) for different thickness of Gold (Au), Silver (Ag) and Copper (Cu) in the range of 20-60nm using finite-difference-time domain (FDTD) analysis. The results show the intensity of the maximum reflectivity (Rmax ) decreased to 3-5% and the minimum reflection intensity (Rmin ) changed from 2-14% depending on the thickness of the metallic layer. The lowest Rmin for each metals contributed by the presence of Cr adhesion layer was 6.06% 40nm Au, 11.7% 30nm Ag and 0.26% 40nm Cu. However, the resonance angle is almost same for all metals without influenced by the presence of ultrathin Cr adhesion layer. The optimum thickness of 50nm Au shows the same and highest sensitivity by 80.56°RIU for structure I and II. The FWHM increased when Cr adhesion layer exist and broadens the SPR curve. Therefore, the ultra-thin chromium layer has influenced the performance of the SPR sensor and highly dependent on the thickness of the metal.