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.