Engineering island-chain silicon nanowires via a droplet mediated Plateau-Rayleigh transformation.

Zhaoguo Xue,Jun Xu,Jimmy Wang,Xiaofan Jiang,Pere Roca I Cabarrocas,Junzhuan Wang,Mingkun Xu,Kunji Chen,Yi Shi,Yaolong Zhao,Linwei Yu

doi:10.1038/ncomms12836

Abstract

The ability to program highly modulated morphology upon silicon nanowires (SiNWs) has been fundamental to explore new phononic and electronic functionalities. We here exploit a nanoscale locomotion of metal droplets to demonstrate a large and readily controllable morphology engineering of crystalline SiNWs, from straight ones into continuous or discrete island-chains, at temperature <350 °C. This has been accomplished via a tin (Sn) droplet mediated in-plane growth where amorphous Si thin film is consumed as precursor to produce crystalline SiNWs. Thanks to a significant interface-stretching effect, a periodic Plateau-Rayleigh instability oscillation can be stimulated in the liquid Sn droplet, and the temporal oscillation of the Sn droplets is translated faithfully, via the deformable liquid/solid deposition interface, into regular spatial modulation upon the SiNWs. Combined with a unique self-alignment and positioning capability, this new strategy could enable a rational design and single-run fabrication of a wide variety of nanowire-based optoelectronic devices.

Highlights

The ability to program highly modulated morphology upon silicon nanowires (SiNWs) has been fundamental to explore new phononic and electronic functionalities
Thanks to an extraordinary large interface-interaction that forces a significant stretching of the liquid catalyst droplet, which is usually unattainable in the typical VLS growth in a gaseous growth environment[24,25], a periodic P-R transformation/oscillation can be stimulated in the Sn droplet and transferred to shape highly modulated SiNWs, from straight ones into continuous or discrete island-chains, all in a single-run low temperature fabrication o350 °C
The samples are first loaded into a plasma-enhanced chemical vapour deposition (PECVD) system and treated by H2 plasma at 250 °C (Fig. 1a) to transform the Sn stripes into discrete Sn droplets with diameters ranging from 200 to 400 nm; a thin layer of hydrogenated amorphous silicon (a-Si:H) is coated at 100 °C (Fig. 1b) to a thickness of 30 to 60 nm, as witnessed in the scanning electron microscopy (s.e.m.) image in Fig. 1d; the samples are annealed at 350 °C in a H2 atmosphere for 20 min, to activate the Sn liquid droplets to kick off the in-plane growth

Summary

Introduction

The ability to program highly modulated morphology upon silicon nanowires (SiNWs) has been fundamental to explore new phononic and electronic functionalities. Thanks to an extraordinary large interface-interaction that forces a significant stretching of the liquid catalyst droplet, which is usually unattainable in the typical VLS growth in a gaseous growth environment[24,25], a periodic P-R transformation/oscillation can be stimulated in the Sn droplet and transferred to shape highly modulated SiNWs, from straight ones into continuous or discrete island-chains, all in a single-run low temperature fabrication o350 °C This unique morphology engineering capability is accompanied with a precise selfpositioning capability, and these combined are advantageous for large scale device connection and deployment

Methods

Results

Conclusion