Functionality of thermally hydrogen-passivated interfaces of oxidized crystalline arrays of Si nanowires on (100) Si

Electron spin resonance studies have been performed on arrays of single-crystalline Si nanowires (NWs), 375 nm long and of top diameter of about 5 nm, fabricated on (100)Si by topdown etching and final thinning by thermal oxidation in dry O2/N2 at 1150 ◦C. The SiO2/SiNW interfaces, showing a density of inherent electrically detrimental Pb0 (Si3 _ Si•) defects substantiallyexceeding that of standard technological (100)Si/SiO2, are of inferior electrical quality. Anextensive study of the passivation kinetics in H2 and forming gas ambient reveals that, even underoptimized conditions, the defect system cannot be inactivated to device grade (at best, 40×improvement in H2), due to the excessive interface stress as exposed by the enhanced spread inactivation energy for hydrogen passivation kinetics. The data reveal the inability, of intrinsicnature, to sufficiently suppress Pb0 defects, preventing to reach device-grade functioning of solarcells using single-crystalline NW arrays on (100)Si in the current state of manufacturing.status: publishe