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首页> 外文期刊>Journal of Heat Transfer >Scaling of Thermal Positioning in Microscale and Nanoscale Bridge Structures
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Scaling of Thermal Positioning in Microscale and Nanoscale Bridge Structures

机译：微尺度和纳米尺度桥梁结构中热定位的缩放

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Heat transfer in a thermally positioned doubly clamped bridge is simulated to obtain a universal scaling for the behavior of microscale and nanoscale bridge structures over a range of dimensions, materials, ambient heat transfer conditions, and heat loads. The simulations use both free molecular and continuum models to define the heat transfer coefficient, h. Two systems are compared: one doubly clamped beam with a length of 100 μm, a width of 10 μm, and a thickness of 3 μm, and a second beam with a length of 10 μm, a width of 1 μm, and a thickness of 300 nm, in the air at a pressure from 0.01 Pa to 2 MPa. The simulations are performed for three materials: crystalline silicon, silicon carbide, and chemical vapor deposition (CVD) diamond. The numerical results show that the displacement and the response of thermally positioned nanoscale devices are strongly influenced by ambient cooling. The displacement depends on the material properties, the geometry of the beam, and the heat transfer coefficient. These results can be collapsed into a single dimensionless center displacement, δ~* = δk/q"αl~2, which depends on the Biot number and the system geometry. The center displacement of the system increases significantly as the bridge length increases, while these variations are negligible when the bridge width and thickness change. In the free molecular model, the center displacement varies significantly with the pressure at high Biot numbers, while it does not depend on cooling gas pressure in the continuum case. The significant variation of center displacement starts at Biot number of 0.1, which occurs at gas pressure of 27 kPa in nanoscale. As the Biot number increases, the dimensionless displacement decreases. The continuum-level effects are scaled with the statistical mechanics effects. Comparison of the dimensionless displacement with the thermal vibration in the system shows that CVD diamond systems may have displacements that are at the level of the thermal noise, while silicon carbide systems will have a higher displacement ratios.
机译：模拟在热定位的双夹式桥梁中的传热，以获得在尺寸，材料，环境传热条件和热负荷范围内微尺度和纳米尺度桥梁结构行为的通用标度。模拟使用自由分子模型和连续体模型来定义传热系数h。比较了两种系统：一种是长度为100μm，宽度为10μm，厚度为3μm的双束光束，另一种是长度为10μm，宽度为1μm，厚度为10μm的光束。 300 nm，在空气中的压力为0.01 Pa至2 MPa。对三种材料执行了仿真：晶体硅，碳化硅和化学气相沉积（CVD）金刚石。数值结果表明，热定位的纳米级器件的位移和响应受到环境冷却的强烈影响。位移取决于材料特性，梁的几何形状以及传热系数。这些结果可以分解为一个单一的无因次中心位移δ〜* =δk/ q“αl〜2，这取决于毕奥数和系统几何形状。随着桥长的增加，系统的中心位移显着增加，而当桥的宽度和厚度变化时，这些变化可以忽略不计；在自由分子模型中，中心位移随着高毕奥数下的压力而显着变化，而在连续情况下，中心位移不依赖于冷却气体压力。位移从0.1的毕奥特数开始，在纳米级的27 kPa气压下发生，随着毕奥特数的增加，无量纲的位移减小，连续水平效应与统计力学效应成比例。系统中的热振动表明CVD金刚石系统的位移可能处于热噪声水平，而硅rbide系统将具有更高的置换率。

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