Use of phosphine as an n-type dopant source for vapor-liquid-solid growth of silicon nanowires

Phosphine (PH ₃) was investigated as an n-type dopant source for Au-catalyzed vapor-liquid-solid (VLS) growth of phosphorus-doped silicon nanowires (SiNWs). Transmission electron microscopy characterization revealed that the as-grown SiNWs were predominately single crystal even at high phosphorus concentrations. Four-point resistance and gate-dependent conductance measurements confirmed that electrically active phosphorus was incorporated into the SiNWs during VLS growth. A transition was observed from p-type conduction for nominally undoped SiNWs to n-ype conduction upon the introduction of PH ₃ to the inlet gas. The resistivity of the n-type SiNWs decreased by approximately 3 orders of magnitude as the inlet PH ₃ to silane (SiH ₄) gas ratio was increased from 2 × 10 ^-5 to 2 × 10 ^-3. These results demonstrate that PH ₃ can be used to produce n-type SiNWs with properties that are suitable for electronic and optoelectronic device applications.