Bandgap and wavefunction engineering of semiconductor heterostructures

磁性半导体(MS)合金等材料和嵌入量子点(QDS)等量子异质结构(QHS)在自旋和光子应用中发挥着重要作用，它们正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化合物QHS的研究，其中包括用于红外光电探测器等光电子器件应用的多层相干量子点的堆栈。我们的研究有很强的实验成分，通常辅之以理论分析和建模。我们已经成功地对材料的物理性质、材料过程和分立器件中的电流传输进行了建模，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固体合作网络来表征它们。我们将使用高分辨率X射线衍射、透射电子显微镜、SQUID磁测量和低温磁输运，以及光学测量的组合，如光吸收、光致发光(PL)、光致发光激发光谱和时间分辨光致发光。这项研究的大部分工作将建立在我们之前在应变III-V化合物(包括稀氮化物)领域的工作的基础上，添加新的有机金属前驱体来生长含铬、锗和锰的合金。因此，在一项单独的提案中要求提供额外资金，以完成和升级专门用于MS合金的金属有机气相外延反应器。我们研究的目标是多方面的，但最相关的是：(I)加强我们对与汽相生长有关的材料属性(结构、光学、磁性和传输)的了解，以及(Ii)在光电和自旋电子应用的创新分立器件设计中设计、改进和应用QHS。新颖的磁性半导体结构将开启控制和操纵载流子自旋的途径，这有望带来新的信息技术。

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.