The effect of growth conditions on the composition and structure of Si1-xGex nanowires grown by the vapor-liquid-solid method using gaseous precursors (SiH4, and GeH4) was investigated. Transmission electron microscopy was used to characterize the structural properties and elemental composition of the nanowires. At higher growth temperatures (>425°C), Ge thin film deposition on the nanowire surface resulted in Au loss during growth and the formation of tapered structures. By simultaneously reducing the growth temperature from 425 to 325 °C to suppress the rate of Ge film deposition and increasing the GeH4/(GeH4 + SiH4) gas ratio, Si1-xGex nanowires were produced with Ge fractions spanning the entire composition range. The Ge fraction follows that predicted from the elemental nanowire growth rates in the Ge-rich (x > 0.5) regime, but deviates to higher Ge fractions in Si-rich (x < 0.5) nanowires. A mechanism was proposed whereby surface diffusion provides an additional pathway to Ge incorporation in Si-rich Si1-xGex. nanowires.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering