银纳米颗粒/多孔硅复合材料的制备与气敏性能研究

采用双槽电化学腐蚀法以电阻率为10-15 Ω·cm的p型<100>晶向的单晶硅片制备了孔径约为1.5 μm, 孔深约为15-20 μm的p型多孔硅, 并以此多孔硅作为基底采用无电沉积法通过调控沉积时间在其表面沉积了不同厚度的银纳米颗粒薄膜. 采用扫描电子显微镜和X 射线衍射仪表征了银纳米颗粒/多孔硅复合材料的形貌和微观结构, 结果表明银纳米颗粒较均匀的分布于多孔硅的表面上且沉积时间对产物的形貌有重要影响. 采用静态配气法在室温下研究了银纳米颗粒/多孔硅复合材料对NH₃的气敏性能. 气敏测试结果表明沉积时间对产物的气敏性能影响较大. 当沉积时间较短时, 适量银纳米颗粒掺杂的多孔硅复合材料由于其较高的比表面积以及特殊的形貌和结构, 对NH₃气体表现出较高的灵敏度、优良的响应/恢复性能. 室温下, 其对50 ppm 的NH₃气体的气敏灵敏度可以达到5.8左右.

Preparation and gas-sensing properties of the silver nanoparticles/porous silicon composite

The p-type porous silicon layer with the aperture about 1.5 microns and hole depth about 15 microns is prepared by electrochemical etching of a p-type monocrystalline silicon wafer with a resistivity 10-15 Ω·cm and along 100] orientation in a double-tank cell which consists of the electrolyte (volume ratio HF: DMF=1:2). Silver nanoparticles film with different thickness has been deposited on porous silicon by the electroless deposition for different deposition times. Morphology and microstructure of the silver nanoparticles/porous silicon composite and ere studied by scanning electron microscope and X ray diffracmeter. Result indicates that the silver nanoparticles are uniformly distributed on the surface of porous silicon and the deposition time has an important influence on the morphology of the composite. The gas-sensing properties of the silver nanoparticles/porous silicon composite to NH₃ are tested at room temperature by the static volumetric method. Results show that the deposition time has a significant impact on the gas-sensing properties of the silver nanoparticles/porous silicon. In a short deposition time, the composite with an appropriate amount of silver nanoparticles doped on the porous silicon shows good gas-sensing properties to NH₃ with high sensitivity, fast response-recovery characteristic due to the high specific surface area and special microstructure. At room temperature, the gas sensor has a sensitivity of about 5.8 to 50 ppm NH₃.