CAREER: Opto- Thermo- Electronic Devices

在几个数量级上精确地改变和控制半导体材料特性的能力已经彻底改变了我们的信息时代。近40年来，半导体器件的研究主要集中在光电性能的优化和控制上，而对热电性能的研究却十分有限。在本研究计划中，我们建议使用相同的带隙工程和薄膜外延技术来改善热特性和设计新的高性能光电元件。提出的研究的核心是基于半导体异质结构和超晶格可以改变电子的平均输运能量，而不是使用大块材料可以实现的。这样的修改与设备参数的明智选择相结合，可以使电子气体从设备的一个区域吸收热能，并将其沉积在靠近散热器的另一个区域。集成的电气、光学和热方法为改善现有设备的性能提供了机会。作为具体的例子，我们将研究器件性能受环境温度变化影响最小的发光二极管和高功率半导体激光器的设计。这项研究将被整合到本科材料特性课程中。在本课程中，学生将进行简单的传输测量，如热传导、霍尔效应或珀尔帖效应。通过为本提案的研究部分开发的输运方程的图形表示，学生将能够看到电子气体如何在半导体中运动，为什么存在Wiedemann-Franz定律，以及如何从一个半导体到另一个半导体产生Peltiereffect。

The ability to change and control precisely material properties ofsemiconductors by several orders of magnitude has revolutionized ourinformation age. While the research in semiconductor devices in the last40 years has been concentrated on the optimization and control of theopto-electronic properties, there has only been a limited work onthermo-electric properties. In this research program, we propose to usesame techniques of bandgap engineering and thin film epitaxy to improvethe thermal characteristics and design novel high performanceoptoelectronic components. The core of proposed research is based on thefact that semiconductor heterostructures and superlattices can modifythe average transport energy of electrons beyond what can be achievedusing bulk material. Such modifications in conjunction with judiciouschoice of device parameters can make the electron gas absorb thermalenergy from one area in the device and deposit it in another area near aheat sink. The integrated electrical, optical and thermal approach givesthe opportunity to improve the performance of existing devices. Asspecific examples, we will study the design of light emitting diodes andhigh power semiconductor lasers in which the device performance is leastaffected by ambient temperature changes. This research will beintegrated in an undergraduate class on Properties of Materials. In thisclass, students will perform simple transport measurements such as heatconduction, Hall or Peltier effect. Through the graphical representationof the transport equation developed for the research part of thisproposal, students will be able to see how the electron gas is movingthrough the semiconductor, why there is Wiedemann-Franz law, and howpassage from one semiconductor to another one gives rise to Peltiereffect.