Positional Control of Crystal Grains in Silicon Thin Film Utilizing Cage-Shaped Protein

Abstract

We have proposed a new crystallization method for silicon thin films utilizing a cage-shaped protein (ferritin), called "bio-nano crystallization", which combines semiconductor processing technology and biotechnology. We utilized nickel nanoparticle-accommodated ferritins as metal catalysts, and succeeded in performing the crystallization. When the ferritin was adsorbed randomly onto the film, crystal nuclei were formed at random places, thus grain position was randomly distributed. In this study, we performed the positional controlled deposition of ferritin by electrostatic interaction for location control of crystal grains. Positively charged areas were formed on negatively charged SiO(2) using 3-amino-propyltriethoxysilane (APTES) as the electrostatic pattern. As a result, we could optimize Ni ferritin concentration to make a large adsorption difference between APTES and amorphous silicon. Therefore, nickel nanoparticles adsorption areas were controlled using APTES patterns. Furthermore, the location control of crystallized areas was achieved by optimizing the concentration of Ni ferritin and the APTES pattern. (C) 2011 The Japan Society of Applied Physics