Low Temperature Crystallization of Amorphous Silicon by Gold Nanoparticle

Abstract

Single crystalline Si thin film fabricated on glass substrate by a process called Solid Phase Crystallization (SPC) is highly desirable for the development of high efficiency and low cost thin film solar cells. However, the use of ordinary soda lime glass requires process temperatures higher than 600 degrees C. Crystallization of Si film at around this temperature takes place in extremely long time exceeding 20 h in most cases. In order to reduce this long process time, new crystallization techniques such as Metal Induced Crystallization (MIC) using thin metal films as a catalyst layer is attracting much attention. Instead of using continuous metal films, the use of metal nanoparticles offers some advantages. In this work, gold thin films were deposited on aluminum doped zinc oxide (AZO) coated glass and then annealed for nanoparticle formation. Amorphous silicon was then deposited by e-beam evaporation onto metal nanoparticles. Silicon films were annealed for crystallization at different temperatures between 500 degrees C and 600 degrees C. We showed that the crystallization occurs at lower temperatures and with higher rates with the inclusion of gold nanoparticles (AuNP). Raman and XRD results indicate that the crystallization starts at temperatures as low as 500 degrees C and an annealing at 600 degrees C for a short process time provides sufficiently good crystallinity. (c) 2013 Elsevier B.V. All rights reserved.