Influence of substrate temperature on the properties of pulsed laser deposited silver nanoparticle thin films and their application in SERS detection of bovine serum albumin

The effect of substrate temperature (Ts) on electrical conductance, surface plasmon resonance (SPR), and surface-enhanced Raman scattering (SERS) activity of silver nanoparticle (AgNP) thin films is presented. AgNP films are grown on glass substrates by pulsed laser deposition in a controlled Ar atmosphere at a pressure of 0.1 mbar and varying Ts. Different Ts results in different morphologies, as observed by scanning electron microscopy. The effect of interparticle distance on the electrical conductance of AgNPs is highlighted. The current–voltage characteristics display negative resistance effect and is attributed to the charge trapping process in AgNPs. The film deposited at room temperature presents a SPR peak at λ = 460 nm, and its wavelength first increases until Ts reaches 300 °C and then decreases with further increasing Ts. The quantitative analysis of SERS studies reveals that SERS intensity of bovine serum albumin (BSA) adsorbed on AgNP substrate deposited at 300 °C exhibits a higher intensity as compared with that of BSA adsorbed on the SERS active substrates at any other Ts.s This study has been partially funded by (1) Portuguese Foundation for Science and Technology (FCT) under the project PTDC/FIS/098943/2008 and strategic project PEST-C/FIS/ UI0607/2011 (2) European COST Actions MP0901-NanoTP and MP0903-NanoAlloy. The authors K.K., K.C.S., J.P.B.S., and G.M. are grateful for financial support through the FCT Grants SFRH/ BPD/87215/2012, SFRH/BPD/68489/2010, SFRH/BPD/92896/2013 and SFRH/BD/72809/2010, respectively. The authors would also like to thank Engineer José Santos for technical support at Thin Film Laboratory