Bandgap and wavefunction engineering of semiconductor heterostructures

磁性半导体（MS）合金等材料和嵌入式量子点（QD）等量子异质结构（QHS）在自旋电子学和光子学应用中发挥着重要作用，并且正在成为技术创新的关键。我的建议将集中在（1）QHS和MS合金的外延生长和（2）它们的表征和在分立器件中的应用。我们将继续我们正在进行的应变III-V族化合物QHS的研究，其中包括多层相干量子点的堆叠，用于光电器件应用，如红外光电探测器。我们的研究有很强的实验成分，通常辅以理论分析和建模。我们已经成功地模拟了分立器件中材料的物理特性、材料工艺和电流传输，并设计了QHS来优化器件性能。 我们将在我们自己的实验室中从气相中生长半导体外延层和纳米结构，并将自己或通过多年来建立的广泛的坚实合作网络对其进行表征。我们将使用高分辨率的X射线衍射，透射电子显微镜，SQUID磁强计和低温磁输运，以及光学测量的组合，如光吸收，光致发光（PL），PL激发光谱和时间分辨PL。这项研究的大部分内容将建立在我们以前在应变III-V族化合物（包括稀氮化物）领域的工作的基础上，并增加新的有机金属前体来生长含Cr，Gd和Mn的合金。因此，在另一项提案中要求提供额外资金，以完成和升级专用于MS合金的金属有机气相外延反应器。我们的研究目标是多方面的，但最相关的是：（i）提高我们对材料性能（结构，光学，磁性和传输）的理解，从气相生长和（ii）设计，改进和应用QHS在创新的分立器件设计光电和自旋电子应用。新型的磁性半导体结构将开辟控制和操纵载流子自旋的途径，有望导致新的信息技术。

Materials such as magnetic semiconductor (MS) alloys, and quantum heterostructures (QHS) such as embedded quantum dots (QDs) play an important role in spintronic and photonic applications, and  are becoming essential for technological innovation. My proposal will focus on (1) the epitaxial growth of QHS and MS alloys and (2) their characterization and application in discrete devices. We will continue our ongoing study of strained III-V compound QHS, which includes stacks of multiple layers of coherent QDs, for optoelectronic device applications such as infrared photodetectors. Our research has a strong experimental component which is usually complemented by theoretical analysis and modeling. We have already successfully modeled physical properties of materials, materials processes, and current transport in discrete devices and designed QHS to optimize device performance.  We will grow the semiconductor epilayers and nanostructures from the vapor phase in our own laboratory, and will characterize them ourselves or through a wide network of solid collaborations established through the years. We will use high-resolution X-ray diffraction, transmission electron microscopy, SQUID magnetometry and low temperature magneto-transport, and a combination of optical measurements such as optical absorption, photoluminescence (PL), PL excitation spectroscopy and time-resolved PL. Most of this research will build upon and extend our previous work in the area of strained III-V compounds (including dilute nitrides), with the addition of new organometallic precursors to grow Cr-, Gd- and Mn-containing alloys. Thus, additional funding is requested in a separate proposal to complete and upgrade a Metal Organic Vapor Phase Epitaxy reactor, dedicated to MS alloys. The objectives of our research are many-fold but the most relevant are:  (i) to enhance our understanding of the material properties (structural, optical, magnetic and transport) in relation to growth from the vapor phase and (ii) to design, improve and apply the QHS in innovative discrete device designs both for optoelectronic and spintronic applications. Novel magnetic semiconductor structures will open pathways to control and manipulate the spin of carriers which is expected to lead to novel information technologies.