Soft Lithographic Approach to the Fabrication of Highly Ordered 2D Arrays of Magnetic Nanoparticles on the Surfaces of Silicon Substrates

作者：Ziyi Zhong, Byron D. Gates, Younan Xia, Dong Qin · 发表于：Langmuir · 年份：2000 · DOI：10.1021/la001211k · 被引用次数：110 · 研究领域：Nanofabrication and Lithography Techniques、Nanomaterials and Printing Technologies、Photonic Crystals and Applications

This paper describes a simple and convenient method that uses patterned monolayers as templates to fabricate highly ordered 2D arrays of magnetic particles (Co, Ni, or α-Fe, and ferrites such as MgFe 2 O 4 or NiFe 2 O 4 ) with lateral dimensions in the range of 70−460 nm. In this method, the hydrophilic, hydroxyl-terminated surface of a Si/SiO 2 wafer was patterned with a hydrophobic monolayer of octadecyltrichlorosilane using microcontact printing with an elastomeric stamp and subsequently used as template to define and deposit a regular 2D array of 2-propanol droplets that contained inorganic salts such as Co(NO 3 ) 2, Ni(NO 3 ) 2, and Fe(NO 3 ) 3, or a combination of these compounds. Evaporation of the solvent led to the formation of a 2D array of nitrate nanoparticles on the hydrophilic, bare regions of Si/SiO 2 . Each nanoparticle could be well-positioned within the hydrophilic region by withdrawing the substrate from the nitrate solution and by letting the solvent evaporate with the wafer being held at a specified orientation relative to the gravitational field. The nitrate was subsequently converted into metal oxide (Co 3 O 4, NiO, and α-Fe 2 O 3 ) by thermal decomposition in air at 600 °C, and finally into a magnetic substance (that is, Co, Ni, and α-Fe) through the reduction by hydrogen gas at 400 °C. The dimensions of these particles could be controlled by changing the concentration of the nitrate solution and/or the area of the hydrophilic region. We have also show...