Optimization of Ag NP’s Fabrication Using RTP for Polycrystalline Si Solar Cell Application

Abstract

The light coupling and scattering property of silver (Ag) nanoparticles (NPs) depend on Ag NPs’ size, shape and interparticle distance of adjacent Ag NPs on the respective silicon (Si) substrate surface. In this Ag NPs’ arrangement onto the Si surface, least surface coverage is always required to minimize the parasitic resistance and enhance light transmission into Si layer which helps to enhance Si solar cell efficiency. In this work, fabrication and optimization of silver (Ag) nanoparticles onto the polycrystalline silicon (pc-Si) have been discussed for enhancing light trapping into Si substrate. Silver NPs of different sizes have been fabricated by using rapid thermal annealing (RTP) of RF deposited Ag thin film on pc-Si surface at RTP temperature of 200, 250, 300, 350 and 400 °C for various annealing durations. A shrinkage force generated at the interface due to the difference in thermal expansion coefficient between Ag thin film and pc-Si surface is responsible for the formation of these Ag NPs. The magnitude of RTP temperature and amount of RTP heat treatment helps in reshaping of Ag NPs, and accordingly, surface coverage by Ag NPs changes onto the pc-Si surface. Experimental results show that minimum surface coverage of 12.17% can be achieved at 400 °C for 35 min RTP treatment which can be utilized for enhancing light trapping property into Si surface.