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Caption : figure s1. low magnification sem image of as-grown zn-seeded si nw and corresponding quantitative eds at 470°c (a) and 340°c (b).

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Caption : figure s2. xrd of the as grown zn-seeded si nws synthesised via the vls mechanism at 470°c (yellow) and the vss mechanism at 340°c (purple). 

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Caption : figure s3. tem imaging of si nws synthesised at 470°c via the vls mechanism showing a diameter increase near the zn seed.

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Caption : figure s4. (a) low magnification tem imaging of a vss grown si nw. (b) tem showing defects in vss grown si nw. (c) higher resolution tem imaging of section indicated by green square in (b) showing evidence intrinsic stacking faults (isf) and extrinsic stacking faults.

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Caption : figure s5. saed’s of different seed types shown in figures 3 including spherical (a), trapezoidal (b) and hexagonal (c). the spots highlighted in green represent the phases for metallic zn with the overlayed si diffraction pattern shown in red.

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Caption : figure s6. higher magnification tem imaging of region with diameter transition of nw shown in figure 4b. ffts obtained from both the vls (i) and vss (ii) segments indicated by green and blue squares respectively, show that no phase changes occur during the diameter transition.

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Caption : figure s7. (a) stem imaging and corresponding edx linescan (b) showing elemental composition of 2-segment nw and zn seed. 

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Caption : figures s8. plot of diameter increase observed for 100 nws with a vls-vss transition and percentage increase.

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Caption : figure s9. (a) bf-tem imaging nw temperature induced vss-vls transition. (b) higher magnification tem image of diameter transition in (a). (c) sem image nw with vss-vls segment with transition indicated by green arrow.

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Caption : figure s10. (a-d) bf-tem imaging of other 3-segment si nws with vls-vss-vls transition.