Hydrogen annealing of arrays of planar and vertically stacked Si nanowires

Four level matrices of round, 35 nm in diameter Si nanowires (NWs) are obtained thanks to a top-down approach. In particular, we report optimized H-2 annealing conditions (800 to 900 degrees C) in order to reconstruct the plasma-etched surfaces of the suspended nanowires. The nanowire shape evolution has been studied in scanning electron microscopy, transmission electron microscopy, and atomic force microscopy. The side roughness decrease and the rounding of the NWs have been quantified. The instability of the anchors of the NWs to the contact regions has been evidenced and confirmed by surface diffusion simulations. (c) 2007 American Institute of Physics.