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

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.