University of Tokyo researchers have announced a new approach for electrical cooling without the need for moving parts.By applying a bias voltage to quantum wells made of the semiconductor aluminum gallium arsenide,electrons can be made to shed some of their heat in a process called"evaporative cooling."Devices based on this principle may be added to electronic circuit boards using conventional semiconductor fabrication methods to help smartphones and laptops avoid performance issues caused by high temperatures.
东京大学的研究人员宣布了一种无需移动部件的电气冷却新方法。通过对半导体铝砷化镓制成的量子阱施加偏置电压，可以使电子在一个称为"蒸发冷却"的过程中散发部分热量——基于这一原理的设备可以使用传统的半导体制造方法添加到电子电路板上，以帮助智能手机和笔记本电脑避免由高温引起的性能问题。
Consumers love portable electronics.But as smartphones,tablets,and laptops become smaller and more powerful,the possibility of overheating becomes an ever more pressing concern.Currently available fans are noisy,bulky,and have moving parts that can fail.Now,scientists at the Institute of Industrial Science,the University of Tokyo have introduced a new,solid-state solution made from semiconductors that could be easily made directly into smartphones or laptops.
消费者喜欢便携式电子产品。但是随着智能手机、平板电脑和笔记本电脑变得越来越小、越来越强大，过热的可能性变成了一个越来越紧迫的问题。目前可用的风扇噪音大，体积大，并有可能失败的移动部件。现在，东京大学(University of Tokyo)工业科学研究所(Institute of Industrial Science)的科学家们推出了一种新型固态半导体溶液，它可以很容易地直接制成智能手机或笔记本电脑。
"Modern portable devices have enabled the current information revolution,"explains one of the first co-authors,Marc Bescond."However,this miniaturization comes with inherent challenges from the waste heat produced.Our new system allows for on-chip cooling using standard semiconductor fabrication processes."
"现代便携式设备使当前的信息革命成为可能，"首批合著者之一 Marc Bescond 解释道。"然而，这种微型化带来了来自产生的废热的内在挑战。我们的新系统允许使用标准的半导体制造工艺在芯片上冷却。"
Quantum wells are nanoscale structures small enough to trap electrons.The type of quantum well used in this research is called an asymmetric double-barrier heterostructure.In these devices,very narrow gallium arsenide wells are separated by layers of aluminum gallium arsenide.When the applied bias voltage is equal to energy of the quantum level inside the well,electrons can use resonant tunneling to easily pass through a barrier.However,only the electrons with high kinetic energies will be able to continue past a second barrier.Since the"hotter"fast-moving electrons escape,while the"cooler"slow electrons become trapped,the device becomes colder.
量子阱是小到足以捕获电子的纳米级结构。研究中使用的量子阱称为非对称双势垒异质结构。在这些设备中，非常狭窄的砷化镓被铝砷化镓层隔开。当施加的偏置电压等于阱内量子能级的能量时，电子可以利用共振隧穿，轻松通过势垒。然而，只有具有高动能的电子才能够继续通过第二个障碍。由于"更热的"快速移动的电子逃逸，而"更冷的"慢速电子被捕获，器件变得更冷。
This"evaporative cooling"is analogous to the process that makes you feel cold when you step out of a swimming pool.The water molecules with the most thermal energy are the first to evaporate off your skin,taking their heat with them.
这种"蒸发式冷却"类似于当你走出游泳池时感到冷的过程。具有最多热能的水分子最先蒸发掉你的皮肤，带走它们的热量。
"We have achieved electron cooling of up to 50 degrees centigrade under ambient conditions.These results make our quantum well devices promising for comprehensive heat management in smart devices,"says senior author Kazuhiko Hirakawa."Future smartphones may come with internal circuit boards packed with even more components,as long as they also have some of these cooling quantum wells."
"在环境条件下，我们实现了电子冷却高达50摄氏度。这些结果使我们的量子阱设备有希望在智能设备中实现全面的热管理，"资深作者 Kazuhiko Hirakawa 说。"未来的智能手机可能会带有内部电路板，其中包含更多的组件，只要它们还有一些这样的冷却量子阱。"
Reference:"Evaporative electron cooling in asymmetric double barrier semiconductor heterostructures"by Aymen Yangui,Marc Bescond,Tifei Yan,Naomi Nagai and Kazuhiko Hirakawa,3 October 2019,Nature Communications.
DOI:10.1038/s41467-019-12488-9
参考文献:Aymen Yangui，Marc Bescond，Tifei Yan，Naomi Nagai and Kazuhiko Hirakawa，2019年10月3日，Nature Communications.DOI:10.1038/s41467-019-12488-9
