Altering Plasmonic Nanoparticle Size Through Thermal Annealing for Improved Photovoltaic Devices

Abstract : We created gold (Au) and silver (Ag) nanoparticles by e-beam deposition on an n-type silicon substrate followed by rapid thermal annealing (RTA) under nitrogen gas. Thermal annealing was performed in two ways: first by varying temperature for a constant time and second by varying time at a constant temperature. RTA under the right eutectic temperature, which varies metal to metal, should create nano-metal particles on the substrate. These nanoparticles were characterized by optical spectroscopy and atomic force microscopy (AFM). Results from the optical measurements provide information on the reflective and absorptive characteristics of Au and Ag nanoparticles. AFM provided additional information about the surface properties including size, density distribution, and other relevant values. Results are reported here and they indicate the nature of the Au and Ag nanoparticles by their optical and surface characterization. We propose that the absorption properties can be obtained in solar cells by exploiting the plasmonic behavior of these nanoparticles.