Temperature at the nanoscale: thermal transport and abrupt interfaces

现代电子设备包含数百万个产生废热的晶体管。消除这些热量已经成为越来越大的挑战。随着芯片上晶体管越来越多、越来越小的趋势继续发展，这一点尤为重要。首席研究员开发了一种新的测温技术，可以测量这些纳米级设备的温度。华氏最初的玻璃汞温度计是从汞的密度变化来推断温度的。这项技术基本上在纳米尺度上做同样的事情。它通过芯片上材料的密度来推断温度的变化。研究小组将使用这项新技术来研究热流如何在导线和界面处流动。参与该项目的学生将接受最先进的纳米制造和显微复制技术的培训。技术摘要：在本项目中，一种新的测温技术将应用于非常小长度尺度的热传输研究，这既不为人所知，又与现代电子学极其相关。这项名为等离子体能量膨胀测温（PEET）的技术包括非常精确地测量材料的密度，然后利用材料热膨胀的知识推断出相应的温度。这种方法基于与华氏最初的玻璃汞温度计相同的原理，也可以从密度变化推断温度。关键的进步是，这里的密度可以用纳米尺度的空间分辨率绘制，这使得该技术能够以前所未有的分辨率绘制温度图。密度是通过在扫描透射电子显微镜（STEM）中使用电子能量损失谱（EELS）测量材料的体等离子体能量来确定的。作为训练的一部分，学生将制作简单的微电子设备。然后，使用电子显微镜，他们将绘制出由电激活设备产生的温度图。通过对电流产生的热梯度进行成像，将有可能直接将原子尺度结构和界面与它们对热量产生和传输的影响联系起来。

Non-technical abstractModern electronic devices contain millions of transistors generating waste heat. Removing this heat has become an increasing challenge. This is particularly important as the trend for both more and smaller transistors on a chip continues. The Principal Investigator has developed a new thermometry technique that allows the temperature of these nanoscale devices to be measured. Fahrenheit's original mercury-in-glass thermometer inferred temperature from the density changes of mercury. This technique does essentially the same thing at the nanoscale. It infers temperature changes from the density of the materials on the chip. The research team will use this new technique to study how heat flows in wires and at interfaces. The students involved in this project will receive training in state-of-the-art nanofabrication and microcopy techniques. Technical abstractIn this project a new thermometry technique will be applied to the study of heat transport at very small length scales, which is both poorly understood and extremely relevant to modern electronics. The technique, plasmon energy expansion thermometry (PEET), involves measuring a material's density very accurately, and then inferring the corresponding temperature using knowledge of the material's thermal expansion. This approach is based on the same principle as Fahrenheit's original mercury-in-glass thermometer, which also infers temperature from density changes. The key advance is that here the density can be mapped with nanoscale spatial resolution, which allows the technique to produce temperature maps with unprecedented resolution. The density is determined by measuring the material's bulk plasmon energy using electron energy loss spectroscopy (EELS) in a scanning transmission electron microscope (STEM). As part of their training, students will fabricate simple microelectronic devices. Then, using the electron microscope, they will map the temperatures that result from electrically activating the devices. By imaging the thermal gradients that result from the electrical currents, it will be possible to directly connect atomic-scale structures and interfaces to the effect they have on heat generation and transport.