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

这主要研究仪器RUI补助金支持仪器研究超快光学和半导体物理以及本科研究培训在麦卡莱斯特学院。仪器是一个7泰萨超导磁体低温恒温器与光学访问。最初的研究将使用该仪器来支持NSF资助的研究半导体中自旋和电荷动力学的计划。这些项目包括半导体自旋动力学的超快太赫兹光谱;半导体磁等离子体振荡的时间分辨测量;以及强驱动半导体量子威尔斯和异质结构中的量子跃迁。PI正在Macalester学院建立一个光谱带宽为0-30 THz的超快THz系统。这一收购将大大加强该系统的能力，允许研究自旋现象和其他磁现象。这些研究项目的共同目标是为高年级本科生提供教育和研究培训机会，并允许在光子学和实验材料物理学方面进行实践培训。学生的研究培训也将通过在高级课程，独立项目和高级荣誉项目中使用该仪器得到加强。随着电子器件中的开关速率被推向更高的频率，理解皮秒和飞秒时间尺度上的半导体中的载流子输运现象变得越来越重要。使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激发半导体，并及时记录电荷的运动。这使得研究半经典现象，如载流子散射和电荷振荡在半导体和半导体异质结构的时间尺度上，这将是至关重要的未来设备。此外，这种技术非常适合于研究量子现象，如半导体量子威尔斯和异质结构中的电子跃迁（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。自旋输运器件，其中电子的自旋，而不是它的电荷，是用来控制传输是强烈的电流感兴趣。其中最有前途的系统是窄隙半导体中的量子威尔斯。

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.