Abnormal thermal effects on the surface plasmon resonance of Ag nanoparticles on the surface of silicon

• Unusual blue shift of the SPR troughs is observed at 343 K.
• Red shift of the SPR troughs is observed at 323 K.
• The mechanism relies on the thermal induced surface electron transport.
• Particle sizes play an important role in the change of the SPR troughs.

The thermal effects on the surface plasmon resonance (SPR) of Ag nanoparticles on the silicon surface have been studied. It is found that unusual blue shifts and narrowing of the SPR troughs occur as the temperature increases from 323 K to 363 K. At low temperature range (from 273 K to 323 K), the SPR troughs have the normal red shifts and broadening as in previous studies. The change of SPR is attributed to the thermal induced electron transport between particles and substrate, and is analyzed using samples with different particle sizes. This work reveals the mechanism of thermal effects on the plasmonic properties of Ag nanoparticles on the surface of silicon and offers useful information for designing of SPR devices.