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采用双槽(自制)电化学腐蚀法在p型单晶硅表面制备多孔硅(PS)层,利用AFM技术分析多孔硅的表面形貌。研究分析了电流密度为20~60 mA/cm2时,多孔硅的孔径、孔深和孔隙率,并分析测试了多孔硅对高浓度乙醇的气敏特性。结果表明,在不同的电流密度腐蚀下,孔径都在10 nm左右;随着电流密度的增加,多孔硅的孔深和孔隙率增大且腐蚀的均匀性较好。当电流密度大于40 mA/cm2后,腐蚀的均匀性开始变差,灵敏度波动较大。通过对多孔硅气体吸附灵敏度的分析,在电流密度为40 mA/cm2时,对各浓度的乙醇气体的灵敏度相对稳定,均值达到2.24×106 kΩ,因此该类样品更适用于MEMS高真空封装的纳米吸气剂。
Porous silicon (PS) layer was prepared on the surface of p-type monocrystalline silicon by double-groove (self-made) electrochemical etching method. The surface morphology of porous silicon was analyzed by AFM. The pore size, pore depth and porosity of porous silicon were investigated at a current density of 20-60 mA / cm2. The gas sensing properties of porous silicon on high concentration ethanol were also analyzed. The results show that the pore diameter is about 10 nm under different current density corrosion. With the increase of current density, the hole depth and porosity of porous silicon increase and the corrosion uniformity is better. When the current density is greater than 40 mA / cm2, the corrosion uniformity begins to deteriorate and the sensitivity fluctuates greatly. The sensitivity of porous silicon gas adsorption analysis, the current density of 40 mA / cm2, the concentration of ethanol gas sensitivity is relatively stable, with an average of 2.24 × 106 kΩ, so these samples are more suitable for high vacuum MEMS packaging Nanometer getter.