Equipment Grant: Superconducting Magnet System for Characterization of New Materials and Devices

磁输运测量已被证明是表征先进半导体材料和器件的最有力方法之一。测量可以提供关于材料和器件的大量信息，如载流子迁移率、载流子密度、电子和空穴的有效质量、弹性和非弹性散射长度、声子发射、栅极电容、层厚度等。为了在明尼苏达大学电气工程系建立这一重要的表征能力，我们建议购买超导磁体系统（SMS），该系统由一个最大磁场为9特斯拉的超导磁体和一个最低冷却温度为1.5K的低温恒温器组成。这样的SMS不仅是必要的，而且对我们目前正在进行的人工结构的新型半导体材料和未来电子器件的研究项目至关重要。本系现有半导体材料与器件专业教师10人；其中至少有五种材料的研究需要用到磁输运表征。利用提案中要求的磁体系统，我们将测量由MBE生长的人工结构晶体中电子和空穴的有效质量；我们将研究利用MBE和超高分辨率电子束光刻技术制造的各种新型量子效应半导体器件的输运；我们将研究人工结构材料中应变对电子和空穴输运性质的影响，以及对半导体器件性能的影响；我们将对δ掺杂MBE生长薄膜进行表征。毫无疑问，不仅上述的研究，而且明尼苏达大学电气工程系的许多其他相关研究都可以从该磁铁系统中受益匪浅。

Magneto-transport measurement has been proven as one of the most powerful methods in charactering advanced semiconductor materials and devices. The measurement can provide vast information about a material and a device, such as carrier mobility, carrier density, effective mass of electrons and holes, elastic and inelastic scattering lengths, phonon emissions, gate capacitance, layer thicknesses, etc. To establish this important characterization capability in Department of Electrical Engineering at University of Minnesota, we propose to purchase a superconducting magnet system (SMS), which consists of a superconducting magnet of the maximum fields of 9 Tesla and a cryostat of the lowest cooling temperature of 1.5K. Such SMS is not only necessary, but also very crucial to our current vigorous ongoing research program on artificially structured new semiconductor materials and devices for future electronics. Currently, our department has total 10 faculty members in the area of semiconductor materials and devices; and at least five of them have great need of using magneto-transport characterization for their research. With a magnet system requested in the proposal, we will measure the effective mass of electrons and holes in artificially structured crystals grown by MBE; we will study the transport in various new quantum-effect-based semiconductor devices fabricated by MBE and ultra-high resolution e-beam lithography; we will investigate the effect of strain in the artificially structured materials on the transport properties of electrons and holes, and on the performance of semiconductor devices; and we will characterize the delta doped MBE grown films. Undoubtedly, not only the listed research but also many other related research in Department of Electrical Engineering at University of Minnesota can benefit greatly from getting this magnet system.