Acquisition of a Magneto-Optical Cryostat for Terahertz Studies of Semiconductor Heterostructures

这项主要的研究仪器瑞资助用于超快光学和半导体物理的研究，以及在Macalester学院的本科生研究培训。该仪器是一台带有光学通道的7特萨超导磁体低温恒温器。初步研究将使用该仪器支持NSF资助的一个项目，该项目旨在研究半导体中的自旋和电荷动力学。这些项目包括半导体自旋动力学的超快太赫兹光谱；半导体中磁等离子体振荡的时间分辨测量；以及强驱动半导体量子井和异质结构中的量子跃迁。PI正在Macalester学院建造一个光谱带宽为0-30 THz的超快太赫兹系统。这项收购将显著增强该系统的能力，使其能够研究自旋现象和其他磁性现象。这些研究项目有一个共同的目标，即为高级本科生提供教育和研究培训机会，并将允许进行光子学和实验材料物理方面的动手培训。通过在高级课程、独立项目和高级荣誉项目中使用该工具，学生的研究培训也将得到加强。随着电子器件的开关频率不断提高，在皮秒和飞秒的时间尺度上理解半导体中的载流子输运现象变得越来越重要。利用超快太赫兹光谱学，可以用飞秒光脉冲或单周期电磁脉冲脉冲激励半导体，并及时记录产生的电荷运动。这使得在时间尺度上研究半导体和半导体异质结中的载流子散射和电荷振荡等半经典现象成为可能，这将是未来器件的关键。此外，这项技术非常适合于研究量子现象，如半导体量子阱中的电子跃迁、异质结构(子带间跃迁)和自旋跃迁。子带间跃迁对于量子相干电子学和中远红外半导体激光器的发展具有重要意义。在自旋输运装置中，电子的自旋而不是其电荷被用来控制输运，这种装置引起了强烈的电流兴趣。其中最有前景的系统是窄禁带半导体中的量子阱。

This Major Research Instrumentation RUI grant supports instrumentation for research in ultrafast optics and semiconductor physics as well as undergraduate research training at Macalester College. The instrumentation is a 7 Tessa superconducting magnet cryostat with optical access. Initial research will use the instrument to support a NSF-funded program to study spin and charge dynamics in semiconductors. The Projects include ultrafast THz spectroscopy of spin-dynamics in semiconductors; time-resolved measurements of magneto-plasma oscillations in semiconductors; and quantum transitions in strongly driven semiconductor quantum wells and heterostructures. The PI is building an ultrafast THz system with spectral bandwidth of 0-30 THz at Macalester College. This acquisition will significantly strengthen the capabilities of the system, permitting investigation of spin phenomena and other magnetic phenomena. The research projects have a common objective of providing education and research training opportunities for advanced undergraduate students and will permit hands-on training in photonics and experimental materials physics. Student research training will also be enhanced through use of the instrument in advanced courses, independent projects and senior honors projects. As the switching rates in electronic devices are pushed to ever-higher frequencies, it becomes increasingly important to understand carrier transport phenomena in semiconductors on picosecond and femtosecond time-scales. Using ultrafast terahertz spectroscopy it is possible to impulsively excite a semiconductor with a femtosecond optical pulse or single-cycle electromagnetic pulse and record the resulting motion of charge in time. This allows the study of semiclassical phenomena such as carrier scattering and charge oscillations in semiconductors and semiconductor heterostructures on time-scales, which will be crucial to future devices. In addition, this technique is well suited to the study of quantum phenomena such as electronic transitions in semiconductor quantum wells and heterostructures (intersubband transitions) and spin transitions. Intersubband transitions are of interest for quantum coherent electronics and for the development of mid- and far-infrared semiconductor lasers. Spin-transport devices in which an electron's spin, rather than its charge, is used to control transport are of intense current interest. Among the most promising systems are quantum wells in narrow-gap semiconductors.