Large-Scale CMOS-Compatible Process for growing Si-BC8 Nanowires

A novel, low temperature process for the growth of silicon nanowires containing a monocrystalline Si-BC8 phase is presented. Silicon atoms in Si-BC8 phase are arranged in body-centered-cubic unit cells resulting into a different energy-wavefactor diagram compared to the silicon diamond cubic phase. Indeed, Si-BC8 possesses a direct band gap as low as 30 meV at room temperature. These characteristics are highly desirable for a large variety of applications, requiring CMOS-compatible manufacturing. The growth was performed in a CVD reactor under exposure to microwaves, and employing Sn nanospheres and SiH ₄ as catalyst and precursor gas, respectively. Microwaves allowed for selective heating of the metal catalyst while keeping the substrate at low temperature. Systematic structural analysis and a phenomenological model for Si-BC8 phase formation are discussed.