Influence of growth time on morphology and structural properties of silicon nanowires grown by VHF-PECVD

In this research, gold catalyzed silicon nanowires (SiNWs) were synthesized on a Si(111) substrate using very high frequency plasma enhanced chemical vapor deposition method based on a vapor–liquid–solid growth mechanism at various growth durations. The results showed that the obtained SiNWs were needle-like shape, which differs from the standard cylindrical nanowire produced by similar techniques. In comparison to the other techniques, Si nanoneedles were synthesized under a lower growth temperature, a lower SiH4 gas flow rate and a higher growth rate. In addition, it was shown that the average length of nanoneedles increased linearly with the growth time. High resolution transition electron microscopy revealed that the nanowires were composed of a crystalline Si core with an amorphous SiO2 shell. Photoluminescence study discovered that the Si nanoneedles exhibit two broad emission bands, which can be attributed to the existence of the shell and the interface between the shell and the core.

► Pure SiH4 gas was used as precursor gas to grow SiNWs using the VHF-PECVD technique.
► SiNWs were synthesized with a lower growth temperature and SiH4 flow rate, and a higher growth rate.
► The SiNWs were needle-like shape with tip diameters ranging from 30 to 50 nm.
► The average length of nanowires was increased linearly with the growth time.