Development of self-assembly method using optical near-field with nano-scale controllability in size and position

在先进的纳米光子器件中，需要纳米波导作为远场/近场转换器件。提出了一种可能的器件，金属纳米粒子等离子体激元波导，并观察到近场能量转移沿着光刻图案化的金属纳米点链。在此，我们利用近场光脱附的新效应，在具有100 nm宽、30 nm深凹槽的玻璃基底上，利用射频溅射技术，在光照下制备了尺寸和位置可控的超长纳米点链。在Al的沉积过程中，具有垂直于凹槽（E_）的线性偏振的2.33-eV光（50 mW）的照射<90>导致以高度尺寸和位置控制的方式形成直径为99.6-nm的Al纳米点链，其间距为27.9-nm，长度为100 μm。纳米点的尺寸和分离的偏差都很小，为5 nm。确定c的位置 关于我们 海恩，我们比较了Al沉积前后玻璃衬底表面的形貌原子力显微镜（AFM）图像。通过形貌比较发现，纳米点链主要形成在边缘附近。此外，在平行偏振E_0下没有获得点结构。由于<90>电场的边缘增强，与E_0相比，E_0的近场强度在凹槽边缘处强烈增强，因此强的近场强度导致纳米点链的形成。在单侧边缘处的点形成源于由于倾斜照明而导致的不对称电场强度分布。在2.62eV（100 mW）的E_2光照射下，用射频溅射Al，观察到Al点链的形成，<90>形成了间距为48.6nm的84.2nm纳米点。虽然周期是类似于在2.33-eV的照明下制造的，点的大小减少成比例的光子能量的增加，表明的大小和位置控制的点链的形成起源于沉积的金属纳米颗粒的解吸。金属点由于等离子体共振而具有强的光吸收，这强烈地依赖于颗粒尺寸。当沉积的金属纳米点达到共振直径时，这可以引起沉积的金属纳米点的解吸。随着金属点的沉积进行，生长受沉积和脱附之间的权衡支配，这取决于入射光的光子能量来确定它们的尺寸。由于纳米点链以基于等离子体共振的尺寸形成，因此所得到的结构应该具有光学近场能量的高传输效率。此外，由于我们的沉积方法是基于光脱附反应，它可以广泛用于制造尺寸和位置控制的纳米结构与其他金属或半导体。少

A nanoscale waveguide is required as a far/near-field conversion device in advanced nanoscale photonic devices. One possible device, a metallic nanoparticle plasmon waveguide, was proposed and near-field energy transfer was observed along the lithographically patterned metallic nanodot chain. Here, we developed the self-assembly of a size- and position-controlled ultra-long nanodot chain using a novel effect of near-field optical desorption.We fabricated a nanodot chain using radio frequency (RF) sputtering under illumination on glass substrate with a 100-nm wide and 30-nm deep groove. During the deposition of Al, illumination of 2.33-eV light (50 mW) with linear polarization perpendicular to the groove (E_<90>) resulted in the formation of a 99.6-nm-diameter Al nanodot chains with 27.9-nm separation that were as long as 100 μm in a highly size- and position-controlled manner. The deviation of both nanodot size and the separation were as small as 5 nm. To identify the position of the c … More hain, we compared topographic atomic force microscopy (AFM) images of the surface of the glass substrate before and after Al deposition. Comparison of the profiles showed that the nanodot chain was formed around edge. Furthermore, no dot structure was obtained with parallel polarization E_0. Since the near-field intensity with E_<90> was strongly enhanced at the edge of the groove in comparison with E_0 owing to edge enhancement of the electrical field, a strong near-field intensity results in nanodot chain formation. The dot formation at the one-sided edge originates from the asymmetric electric-field intensity distribution, owing to the slanted illumination. This prediction is supported by calculations.Al-dot chain formation was also observed with RF sputtering of Al under illumination of a 2.62-eV light (100 mW) with E_<90>, which resulted in the formation of 84.2-nm nanodot with 48.6-nm separation. Although the period was similar to that fabricated under 2.33-eV illumination, the dot size was reduced in proportion to the increase in the photon energy, indicating that the size- and position-controlled dot-chain formation originates from desorption of the deposited metallic nanoparticles. A metallic dot has a strong optical absorption due to plasmon resonance, which strongly depends on particle size. This can induce desorption of the deposited metallic nanodot when it reaches the resonant diameter. As the deposition of metallic dots proceeds, the growth is governed by a trade-off between deposition and desorption, which determines their size, depending on the photon energy of the incident light.Since the nanodot chain forms at the size based on plasmon resonance, the resulting structure should have high transmission efficiency of optical near-field energy. Furthermore, since our deposition method is based on a photo-desorption reaction, it could be widely used to fabricate size- and position-controlled nanoscale structures with other metals or semiconductors. Less