In this study, Ag nanoislands were deposited on glass and Si(100) at substrate
temperature from 25 to 450 °C by Pulsed Laser Depositions (PLD). The growth of Ag
nanoislands was evidenced from optical absorption surface plasmon resonance (SPR) bands.
SPR peaks was not evidently observed in the spectrum of sample deposited at 25 °C, but
sample deposited at 150 °C presented a broad SPR peak around λ=870 nm. SPR peak showed
a blue shift to 540-550 nm and became narrower as the substrate temperature increases.
Atomic Force Microscope (AFM) showed that by increasing deposition temperature to 350
and 450 °C, Ag islands grow in height and diameter and the number of island decrease among
the surface. Two-probe measurement of electrical resistance of films was also recorded during
deposition processes to recognize the coalescence of Ag nanoislands. The results show that
the deposition at temperatures below 250 °C leads to a sharp decrease in film resistance while
at higher temperatures the islands were separated without resistance decline. To determine
coalescence threshold temperature, resistance variation was measured for a cooling substrate,
from 300 down to 200 °C, substrate. The result revealed that the coalescence of Ag begins
near 230 °C.
Keywords: Ag nanoisland; PLD; coalescence; SPR; resistance measurement
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