Strain engineering of core-shell silicon carbide nanowires for mechanical and piezoresistive characterizations
Strain engineering of core-shell silicon carbide nanowires for mechanical and piezoresistive characterizations
复制标题
用于机械和压阻表征的核壳碳化硅纳米线的应变工程
DOI：
10.1088/1361-6528/ab0d5d
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发表时间：
2019
期刊：
影响因子：
3.5
通讯作者：
Alois Lugstein and Yoshitada Isono
中科院分区：
文献类型：
--
作者：
Shinya Nakata;Akio Uesugi ;Koji Sugano;Francesca Rossi;Giancarlo Salviati;Alois Lugstein and Yoshitada Isono
本研究对采用气-液-固三相法合成的核壳结构碳化硅纳米线(C/S-SiCNW)的力学性能和压阻性能进行了研究。C/S-SiCNW是由无定形二氧化硅(SiOx)壳层包裹的立方晶型(3C)碳化硅核心层组成的，但透射电子显微镜观察表明，由于Shockley部分位错，层错在核心层中诱导了部分六方多型体(2H、4H和6H)。用基于MEMS的纳米拉伸试验研究了C/S-SiCNW和不含SiOx壳的碳化硅芯材的应力-应变关系。C/S-SiCNW和碳化硅芯材的平均抗拉强度分别为7.0 GPA和22.4 GPA。C/S-SiCNW强度较低的原因是以表面粗糙度为断裂点的SiOx壳层。C/S-SiCNW的杨氏模数平均值为247.2 Gpa，而碳化硅芯材的杨氏模数较大，其散射值在450~580 Gpa之间。基于透射电子显微镜观察的碳化硅磁芯的几何模型通过磁芯中层错的体积含量对这种散射数据进行了合理化。从单轴拉伸下的I-V特性评价了C/S-SiCNW和碳化硅芯材的压阻效应。在0.008ε时，C/S-SiCNW的规范系数为-30.7%，是碳化硅芯材在0.01ε时的-15.8值的两倍左右。这可能是由于SiOx壳层的正固定氧化物电荷增加了SiOx/SiC界面的表面态密度所致。
This study evaluated the mechanical properties and piezoresistivity of core–shell silicon carbide nanowires (C/S-SiCNWs) synthesized by a vapor–liquid–solid technique, which are a promising material for harsh environmental micro electromechanical systems (MEMS) applications. The C/S-SiCNWs were composed of a crystalline cubic (3C) SiC core wrapped by an amorphous silicon dioxide (SiO x) shell; however, TEM observations of the NWs showed that hexagonal polytypes (2H, 4H, and 6H) were partially induced in the core by a stacking fault owing to a Shockley partial dislocation. The stress–strain relationship of the C/S-SiCNWs and SiC cores without an SiO x shell was examined using MEMS-based nanotensile tests. The tensile strengths of the C/S-SiCNWs and SiC cores were 7.0 GPa and 22.4 GPa on average, respectively. The lower strength of the C/S-SiCNWs could be attributed to the SiO x shell with the surface roughness as the breaking point. The Young's modulus of the C/S-SiCNWs was 247.2 GPa on average, whereas that of the SiC cores had a large value with scatter data ranging from 450 to 580 GPa. The geometrical model of the SiC core based on the transmission electron microscopy observations rationalized this scatter data by the volume content of the stacking fault in the core. The piezoresistive effects of the C/S-SiCNW and SiC core were also evaluated from the I–V characteristics under uniaxial tensile strain. The gauge factor of–30.7 at 0.008 ε for the C/S-SiCNW was approximately two-times larger than that of–15.8 at 0.01 ε for the SiC core. This could be caused by an increase of the surface state density at the SiO x/SiC interface owing to the positive fixed oxide charge of the SiO x shell.