Comparative study of the effects of phosphorus and boron doping in vapor–liquid–solid growth with fixed flow of silicon gas

• n-Si and p-Si microneedles were grown by VLS with phosphorus and boron doping.
• Properties of doped Si microneedles were measured and compared with doping.
• The growth success with boron doping was higher than with phosphorus doping.
• Phosphorus doped Si microneedle provides better electrical properties than boron.

This work was carried out to investigate the comparative effects of phosphorus and boron doing in vapor–liquid–solid (VLS) growth. Doped Si microneedles were grown by VLS mechanism at the temperature of 700 °C or less using Au as the catalyst. VLS growth using in-situ doping with the mixed gas of Si2H6 and PH3 produced phosphorus doped n-Si microneedles at Au dot sites, whereas, the mixed gas of Si2H6 and B2H6 produced boron doped p-Si microneedles. The variation of growth rate, diameter, resistivity, impurity concentration and carrier (electron, hole) mobility of these n-Si and p-Si microneeedles were investigated and compared with the variation of dopant gas (PH3 or B2H6) flow, with a fixed flow of Si gas (Si2H6). This comparative study shall be helpful while fabricating devices by growing n-Si and p-Si microneedles one above another by multistep (2-step or 3-step) VLS growth.