应用于SERS的针尖状硅纳米线的生长与形貌调制（英文）

Growth and Morphology Modulation of Needle-like Silicon Nanowires for SERS Application

半导体纳米线作为一种潜在的表面增强拉曼光谱(SERS)基底材料正受到广泛的关注。本文采用金作为催化剂,通过等离子体增强化学气相沉积系统,以气-液-固生长机制制备一种直径可控的针尖状硅纳米线。基于合金液滴控制硅纳米线形貌的事实,通过设计调节合金催化剂的尺寸,制备了针尖状硅纳米线。所制备硅纳米线形貌通过SEM清晰可见,为针尖状。TEM和XRD分析表明,硅纳米线为同轴结构,单晶硅核包覆非晶SiO_2壳层。作为SERS活性基底,通过伽伐尼置换在纳米线表面沉积活性Ag颗粒,同等条件下对R6G的检测显示,针尖状硅纳米线基底其增强因子是柱状硅纳米线的十多倍。由此预测,这种针尖状的硅纳米线可应用于新型传感器、环境监测、生物医疗诊断等领域。此外,这种针尖硅纳米线的制备方法也可以用作制备其他的针尖状纳米线,例如同族的锗针尖纳米线等等。

Semiconductor nanowires are attracting intense interest as a promising substrate material for surface enhanced Raman spectroscopy（SERS）.Based on vapor-liquid-solid（VLS） procedure using Au as a catalyst,silicon nanowires（SiNWs） with controllable diameters were developed by the plasma enhanced chemical vapor deposition（PECVD） system.Inspired by the fact that the morphology of SiNWs can be effectively modulated by tuning the size of catalyst droplets,we designed a needle-like SiNWs owing to the shrink and consumption of Si-Au catalyst droplets.Transmission electron microscopy（TEM） and X-ray diffraction（XRD） analyses reveal that crystalline Si phase is possessed of amorphous SiO2 in the as-prepared coaxial nanowires.The morphology of the prepared SiNWs was examined by scanning electron microscope（SEM）.As SERS active substrates,Ag nanoparticles were synthesized on surface of SiNWs by galvanic displacement.Results show that enhancement factor（EF） of SERS achieved on the prepared needle-like SiNWs/Ag is more than 10 times than that of cylindrical-shaped SiNWs/Ag for R6 G molecules detection.It is supposed that needle-like SiNWs composited with Ag nanoparticles can be exploited as a new type nanosensor,environmental monitoring or biomedical diagnostics.In addition,many other needle-like semiconductor nanowires such as germanium needle-like nanowires also can be prepared by similar method in the present study.