氧化钒/多孔硅/硅结构的微观形貌、纳米力学及温敏特性

Microstructure, Nano-Mechanical and Temperature Sensitive Properties of VOx/Porous Silicon/Si Structure

采用电化学腐蚀法在硅基片表面形成多孔硅,利用直流对靶反应磁控溅射方法在不同电流密度条件下制备的多孔硅样品表面上溅射沉积了VOx薄膜,获得了氧化钒/多孔硅/硅(VOx/PS/Si)结构.采用场发射扫描电镜(FESEM)观测多孔硅及VOx/PS/Si结构的微观形貌,采用纳米压痕仪器测量VOx/PS/Si结构的纳米力学特性,通过电阻-功率曲线分析研究其温度敏感特性.实验结果表明,在40和80mA·cm-2电流密度下制备多孔硅的平均孔径分别为18和24nm,用显微拉曼光谱法(MRS)测量其热导率分别为3.282和1.278kW·K-1;VOx/PS/Si结构的电阻随功率变化的平均速率分别为60×109和100×109Ω·W-1,VOx/PS/Si结构的显微硬度分别为1.917和0.928GPa.实验结果表明,多孔硅的微观形貌对VOx/PS/Si结构的纳米力学及温敏特性有很大的影响,大孔隙率多孔硅基底上制备的VOx/PS/Si结构比小孔隙率多孔硅基底上制备的具有更高的温度灵敏度,但其机械稳定性也随之下降.

Porous silicon （PS） was formed on the surface of silicon wafer by electrochemical etching method under different current densities. In order to form VOx/PS/Si structure, vanadium oxide thin films were deposited on PS surface utilizing novel facing targets DC reactive sputtering technique. Field emission scanning electron microscope （FESEM） was utilized to observe the microstructure of PS and VOx/PS/Si structure, the nano-mechanical property of VOx/PS/Si structure was studied by nanoindentor instrument, and the temperature sensitive property was analyzed with resistance-power curves. The results showed that the average pore sizes of PS samples prepared under current densities of 40 and 80 mA·cm^-2 were 18 and 24 nm, and the thermal conductivities tested by micro Rarnan spectroscopy were 3.282 and 1.278 kW·K^-1, respectively. The average speeds of resistance varying with power for VOJPS/Si structure were 60×10^9 and 100×10^9Ω.W^-1, and the nano-hardness were 1.917 and 0.928 GPa, respectively. The experimental results indicated that the microstructure of PS had great influence on the nano-mechanical property and temperature sensitivity of VOJPS/Si structure; this structure formed on PS with high porosity had better temperature sensitivity than PS with low porosity, but a worse mechanical stability.