Facile synthesis of Ge1−xSnx nanowires

Ying Xu,Teck Hock Lim,Richard D Tilley,Najeh Al-Salim,Soshan Cheong,Chris W Bumby

doi:10.1088/2053-1591/ab96fb

Abstract

We report a facile one-pot solution phase synthesis of one-dimensional Ge1−xSnx nanowires. These nanowires were synthesized in situ via a solution-liquid-solid (SLS) approach in which triphenylchlorogermane was reduced by sodium borohydride in the presence of tin nanoparticle seeds. Straight Ge1−xSnx nanowires were obtained with an average diameter of 60 ± 20 nm and an approximate aspect ratio of 100. Energy-dispersive x-ray spectroscopy (EDX) and powder x-ray diffraction (PXRD) analysis revealed that tin was homogeneously incorporated within the germanium lattices at levels up to 10 at%, resulting in a measured lattice constant of 0.5742 nm. The crystal structure and growth orientation of the nanowires were investigated using high-resolution transmission electron microscopy (HRTEM). The nanowires adopted a face-centred-cubic structure with individual wires exhibiting growth along either the 〈111〉, 〈110〉 or 〈112〉 directions, in common with other group IV nanowires. Growth in the 〈112〉 direction was found to be accompanied by longitudinal planar twin defects.

Highlights

Ge1−xSnx has attracted much research interest as an exciting material with potential applications in nextgeneration rechargeable lithium-ion battery anodes and optoelectronic devices, due to their high carrier mobilities [1,2,3] and a direct band gap which can be tuned by varying the tin concentration [4,5,6,7,8,9,10,11,12]
Geaney et al and Mullane et al have reported the synthesis of germanium nanowires using tin catalyst seeds at a decomposition temperature of more than 350 °C, but no Ge1−xSnx was formed in these processes [30, 31]
scanning electron microscopy (SEM) images in figures 1(a) and S1 is available online at stacks.iop.org/MRX/7/064004/mmedia reveal that the synthesized material contained a high yield of Ge1−xSnx nanowires

Summary

Introduction

Ge1−xSnx has attracted much research interest as an exciting material with potential applications in nextgeneration rechargeable lithium-ion battery anodes and optoelectronic devices, due to their high carrier mobilities [1,2,3] and a direct band gap which can be tuned by varying the tin concentration [4,5,6,7,8,9,10,11,12]. Ge1−xSnx alloys are commonly fabricated using ion implantation, laser melting [4, 5, 19], molecular beam epitaxy (MBE) [7], and chemical-vapor deposition(CVD) approaches [6, 20,21,22]. In order to fabricate Ge1−xSnx nanowires incorporating high tin content, non-equilibrium introduction of tin into the germanium lattice has been proposed and demonstrated by several groups. These used either a VLS mechanism from liquid-injection CVD upon Au [18] or AuAg catalysts [12, 26], or IPSLS approach [23, 27]. Reports focused on self-seeded SLS growth of high quality Ge1−xSnx nanowires from tin catalyst are rare

Methods

Results

Conclusion