Nanowire heterostructures for intersubband lasers

这项研究的目的是研究在室温下工作的太赫兹激光器中生长的半导体纳米线中的量子点。半导体量子点材料由于能显著抑制光学声子散射辅助的电子能量弛豫而成为子能级间探测器和发射体的极佳候选者。合作研究工作将分三个阶段进行：(I)合理生长纳米线中的轴向和核/壳异质结构以形成耦合量子点，(Ii)利用红外光谱测量和表征纳米线的亚能级间吸收，以及(Iii)研究用于电致发光和受激发射的纳米线量子点超晶格。智能上的优点是将纳米线量子点用于亚能级间级联激光器，这有望解决传统平面THz量子级联激光器的一个基本限制，在这种激光器中，非辐射声子辅助驰豫阻止了室温操作。无金属催化剂的选区MOCVD外延将用于生长高深宽比的InGaAs/GaAs半导体纳米线，使用光刻定义的氧化物生长掩模，并嵌入轴向量子点以实现高效的点到点隧道传输。更广泛的影响是开发一类具有高度可工程化量子电子性质的低维III-V半导体纳米材料。这项工作将推动太赫兹材料和技术的发展，在这些材料和技术中，需要光源和探测器来进行传感、成像和光谱分析。该计划还将通过实验室研究参与、补充课程开发和以科学为重点的社区K？12参与，将教育和研究整合到本科生/研究生的培训中。已经制定了一项计划，通过学生代表不足的少数族裔协会和加州大学洛杉矶分校工程卓越和多样性中心集中招聘本科生研究人员。

The objective of this research is to investigate quantum-dots grown within semiconductor nanowires for terahertz lasers that operate at room-temperature. Semiconductor quantum-dot materials are excellent candidates for intersublevel detectors and emitters because of their dramatic suppression of electronic energy relaxation assisted by optical-phonon scattering. A collaborative research effort will proceed in three stages: (i) rational growth of axial and core/shell heterostructures in nanowires for the formation of coupled-quantum dots, (ii) measurement and characterization of nanowire intersublevel absorption using infrared spectroscopy, and (iii) investigation of nanowire quantum-dot superlattices for electroluminescence and stimulated emission. The intellectual merit is the use of nanowire quantum-dots for intersublevel cascade lasers, which are expected to solve a fundamental limitation of conventional planar THz quantum-cascade lasers, where non-radiative phonon-assisted relaxation prevents room temperature operation. Selective-area MOCVD epitaxy without metal catalysts will be used to grow high-aspect ratio InGaAs/GaAs semiconductor nanowires using lithographically defined oxide growth masks, with embedded axial quantum dots for efficient dot-to-dot tunneling transport. The broader impacts are the development of a class of low-dimensional III-V semiconductor nanomaterials with highly engineerable quantum-electronic properties. This work will advance terahertz materials and technology, where sources and detectors are desired for sensing, imaging, and spectroscopy. The program will also integrate education and research in training of undergraduate/graduate students through laboratory research participation, complementary coursework development, and scientifically focused community K?12 involvement. A plan is in place for focused recruiting of undergraduate student researchers through student underrepresented minority societies and the UCLA Center for Engineering Excellence and Diversity.