Figure 2. U-shaped KNWs.

a, Schematic of a U-shaped KNW with tip constructed from three 120° cis-linked kinks. The lightly-doped n-type nanoFET element (pink) is encoded at the tip and connected by heavily-doped n⁺⁺ S/D arms (blue). The grey arrows indicate the growth sequence for the nanostructure. (b) SEM images of original (I: scale bare, 2 μm) and KOH-etched (II: scale bar, 500 nm) U-shaped KNW synthesized with 80 nm diameter Au-NP catalysts. Red arrow marks the position of nanoFET element between the second and the third cis-linked kinks. c, Representative SEM image of a U-shaped KNW prepared using 30 nm diameter Au-NPs. The measured nanowire diameter is 30 nm. Scale bar, 1 μm.. d, SEM images of 3D probe devices fabricated using a 30 nm diameter U-shaped (left) and 150 nm diameter V-shaped (right) KNW building blocks. Scale bars, 3 μm. e, Conductance versus water-gate reference potential data recorded from a representative 30 nm diameter U-shaped KNW 3D probe in 1× phosphate buffer saline (PBS).³⁷