Casimir Force Contrast Between Amorphous and Crystalline Phases of AIST
Casimir Force Contrast Between Amorphous and Crystalline Phases of AIST
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DOI：
10.1002/adfm.201200641
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发表时间：
2012-09
影响因子：
19
通讯作者：
G. Torricelli;P. J. van Zwol;O. Shpak;G. Palasantzas;V. Svetovoy;C. Binns;B. Kooi;P. Jost;M. Wuttig
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文献类型：
--
作者：
G. Torricelli;P. J. van Zwol;O. Shpak;G. Palasantzas;V. Svetovoy;C. Binns;B. Kooi;P. Jost;M. Wuttig
相变材料（PCM）可以在非晶态和晶态之间快速可逆地转换。结构转变伴随着光学和电子性质的显著变化，使得PCM适合于可编程光学数据存储和非易失性电子存储器。相变还伴随着结晶时金和AIST（Ag5In5Sb60Te30）之间的卡西米尔力增加20%至25%。在这里，重点是再现和理解所观察到的卡西米尔力的变化，这被证明是相关的结晶后的介电函数的变化。介电函数在两个独立的频率范围内变化：可见光范围内吸收的增加是由于共振键合，这是结晶相所特有的，而自由载流子吸收是红外区变化的原因。结果表明，自由载流子对力对比度的贡献约为50%，而另一半则来自共振成键。这有助于识别使力对比度最大化的PCM。最后，它表明，如果这个概念的力控制是采用在微机电设备，那么保护盖层的PCM必须只有几个纳米厚，以尽量减少力的对比度。
Phase change materials (PCMs) can be rapidly and reversibly switched between the amorphous and crystalline state. The structural transformation is accompanied by a significant change of optical and electronic properties rendering PCMs suitable for rewritable optical data storage and non‐volatile electronic memories. The phase transformation is also accompanied by an increase of the Casimir force of 20 to 25% between gold and AIST (Ag5In5Sb60Te30) upon crystallization. Here the focus is on reproducing and understanding the observed change in Casimir force, which is shown to be related to a change of the dielectric function upon crystallization. The dielectric function changes in two separate frequency ranges: the increase of absorption in the visible range is due to resonance bonding, which is unique for the crystalline phase, while free carrier absorption is responsible for changes in the infrared regime. It is shown that free carriers contribute ≈50% to the force contrast, while the other half comes from resonance bonding. This helps to identify PCMs that maximize force contrast. Finally it is shown that if this concept of force control is to be employed in microelectromechanical devices, then protective capping layers of PCMs must be only a few nanometers thick to minimize reduction of the force contrast.