Functionalization of silicon nanowires with transition metal atoms

Abstract

This paper investigates atomic structure, mechanical, electronic, and magnetic properties of silicon nanowires (SiNW) using first-principles plane-wave calculations within density-functional theory. We considered bare, hydrogen-terminated, and $3d$-transition metal (TM) adsorbed SiNWs oriented along [001] direction. We also studied Cr interstitial impurity. Nanowires of different sizes are initially cut from the bulk Si crystal in rodlike forms, and subsequently their atomic structures are relaxed before and also after the termination of surface dangling bonds by hydrogen atoms. We first presented an extensive analysis of the atomic structure, stability, elastic, and electronic properties of bare and hydrogen-terminated SiNWs. The energetics of adsorption and resulting electronic and magnetic properties are examined for different levels of $3d$-TM atom coverage. Adsorption of TM atoms generally results in magnetic ground state. The net magnetic moment increases with increasing coverage. While specific SiNWs acquire half-metallic behavior at low coverage, at high coverage ferromagnetic nanowires become metallic for both spin directions, and some of them have very high spin polarization at the Fermi level. Our results suggest that the electronic and spintronic devices with conducting interconnects between them can be fabricated on a single SiNW at a desired order. We believe that our study will initiate new research on spintronic applications of SiNWs.