A novel method for the production of highly adherent Au layers on glass substrates used in surface plasmon resonance analysis: substitution of Cr or Ti intermediate layers with Ag layer followed by an optimal annealing treatment

The adherence of sputtered Au layers on glass substrates used for surface plasmon resonance (SPR) analysis is very weak. This is usually compensated using a thin Cr or Ti intermediate layer. In this study, a 10-nm sputtered Ag layer (instead of usual Cr or Ti layer) was used as an adhesive intermediate layer between the 40-nm Au layer and the glass substrate. The effect of successive heat treatment at different temperatures on the Au layer adherence and SPR resonance characteristics has been studied. Pull off tests and stability against treatment in boiling water tests have been used for the assessment of Au layer adherence. Based on SPR analysis and pull off and boiling water tests, it is shown that an optimum annealing temperature of 250°C exists for which the Au/Ag/glass substrate composite layer possesses a reasonable adherence along SPR sensitivity.