Structural characteristics and connection mechanism of gold-catalyzed bridging silicon nanowires

Lateral, single-crystalline silicon nanowires were synthesized using chemical vapor deposition catalyzed by gold nanoparticles deposited on one of the vertical {1 1 1} sidewalls of trenches etched in Si(0 1 1) substrates. Upon encountering the opposing sidewalls of the trenches, the lateral nanowires formed a mechanically strong connection. The bridging connection at the opposing sidewall was observed using high-resolution transmission electron microscopy (TEM) to be epitaxial and unstrained silicon-to-silicon. Using energy-dispersive X-ray spectroscopy in TEM, gold could not be detected at the interface region where the nanowires formed a connection with the opposing sidewall silicon deposit but was detected on the surface adjacent to the impingement region. We postulate that a silicon-to-silicon connection is formed as the gold–silicon liquid eutectic is forced out of the region between the growing nanowire and the opposing sidewall.     

Annealing of chemically vapor deposited nanoscale Ti-Si islands on Si

Small islands of Ti-Si were formed by chemical vapor deposition onto a Si substrate and subsequently annealed. The islands were deposited in the 610–730 °C temperature range by the H₂ reduction of TiCl₄, either without or with a Si-containing gas added during deposition. Subsequent annealing above 800 °C decreases the island density significantly, and the islands take characteristic shapes. After annealing, the island size depends only weakly on the amount of Ti deposited while the island density varies more significantly and depends on the addition of a Si-containing gas during deposition. Three different dominant island shapes are seen on Si(001), and different shapes are found on Si(111). PACS 68.60.Dv; 68.65.Hb; 68.35.Fx