Cylindrical Line-Feeding Growth of Free-Standing Silicon Nanohelices as Elastic Springs and Resonators

Abstract

Three-dimensional (3D) construction of free-standing silicon (Si) nanohelices has been a formidable challenge for planar lithography and etching technology. We here demonstrate a convenient 3D growth and integration of Si nanohelices (SiNHs) upon bamboolike cylinders with corrugated sidewall grooves, where the indium catalyst droplets grow around the cylinders in a helical fashion, while consuming precoated amorphous Si (a-Si) thin film to produce crystalline Si nanowires on the sidewalls. At the end of each groove cycle, the droplets are enforced to linefeed/switch into the neighbor groove to continue a spiral growth of SiNHs with readily tunable diameter, pitch, aspect-ratio, and chiral/achiral symmetries. In addition, the SiNHs can be reliably released as free-standing units to serve as elastic links, supports and vibrational resonators. These results highlight the unexplored potential of high precision 3D self-assembly growth in constructing a wide range of sophisticated electromechanical, sensor, and optoelectronic functionalities.

Helical SiNW design with a dual-peak response for broadband scattering in translucent solar cells

“…19 The helical SiNWs and helical nanowires of other materials can also be prepared in the experiment. [30][31][32][33][34] Therefore, it is possible to prepare translucent helical SiNW array solar cells in the experiment. The PEDOT:PSS film forms a heterojunction on the top of SiNWs.…”

Highly Stretchable High‐Performance Silicon Nanowire Field Effect Transistors Integrated on Elastomer Substrates

“…In order to batch‐fabricate ultrathin ( D nw < 80 nm), high quality and, more importantly, self‐positioned orderly SiNW array, we have developed, in our previous works, a relatively new in‐plane solid‐liquid‐solid (IPSLS) growth mechanism, [ 33 , 34 , 35 , 36 , 37 , 38 ] where indium (In) catalyst droplets can be guided by pre‐defined edge lines to produce planar SiNWs at precise locations, by consuming precoated amorphous Si (a‐Si) precursor layer on substrate surface. Though high‐performance SiNW‐FETs have been successfully demonstrated, [ 37 , 39 , 40 , 41 , 42 , 43 ] based on the high crystallinity 1D channels grown at a rather low temperature <350 °C, a stretchable integration of these SiNW FETs onto soft elastomer thin film substrate, within a hard‐island‐protection architecture, has not been investigated.…”

Designable Integration of Silicide Nanowire Springs as Ultra‐Compact and Stretchable Electronic Interconnections

“…In this study, we develop a growth integration strategy to batch‐manufacture orderly array of ultrathin and highly conductive Si‐Ni alloy nanowire springs (SiNi x ‐NS), with precise location control and designable elastic channel shapes. The SiNW frameworks were first formed via a step‐edge guided planar growth, based on an in‐plane solid–liquid–solid (IPSLS) mechanism established in our previous works, [ 48–57 ] followed by a low temperature alloy forming annealing that transforms the SiNWs into highly conductive Si‐Ni alloy channels, while preserving faithfully the elastic shapes. In this way, ultrathin SiNi x ‐NS channels with diameter ≈160 nm and small curvature radius <1.5 µm can be reliably fabricated, without the use of any high precision EBL or NIL technologies.…”