Collaborative Research: Chemisorption-Induced Ultraviolet Quantum Well Optoelectronic Materials

非技术描述：下一代设备需要能够推进（多）功能响应的新型材料。在这方面，复合氧化物材料和界面具有潜在的深远影响。特别令人感兴趣的是利用新的光-物质相互作用来实现一系列应用的机会。控制这种相互作用需要严格的材料生产和对现象背后机制的深入理解。例如，半导体异质结构驱动光电子器件用于固态照明、通信、计算和传感，随后氮化物和简单氧化物基材料的引入有助于将这些技术推向紫外线发射范围。涉及紫外线发射装置的新功能可能使信息的编码和操作更快，化学检测和传感的新模式，以及更有效的固态照明。该项目通过局部材料重构探索了按需复杂氧化物电子的机会。它建立在两个绝缘体界面电导率的发现之上，并展示了可逆的、局部的电导率操纵，从而从这些材料中产生可调谐的紫外线发射。该项目积极促进在对美国持续经济活力至关重要的重要技术和相关领域培养下一代科学家和工程师，重点关注对历史上代表性不足的群体的学生进行指导和培训，并为学员提供合作研究和国际研究经验。技术描述：在这个项目中，一种新的光电材料范例被定义为空间和化学选择性化学吸附与在两个带绝缘体的界面上形成的亚表面量子阱的耦合。在一个界面上，组成半导体之间的对称性破坏和静电势失配导致了在体中无法实现的新现象。在某些系统中，这种突现现象可以被广泛地调整，因为一个表面，在某种程度上，一个界面，可以自由地在结构上和电子上重建。在受控环境下使表面或次表面达到平衡，可以实现对电子相位或功能状态的局部可逆控制。本文研究了降低对称场的吸附质类型和位置对一个或多个不同的次表面二维电子液体紫外发光的强度、能量和空间响应的影响。特别是，这些活动集中在理解和最终控制几个显著特征：1)稳态紫外光发射强度如何响应不同的吸附；2)通过光谱发射变化探测模型系统的物理性质如何响应外部外加场；3)如何在外界刺激下控制紫外线发光，包括局部性和稳定性；4)引入多个紧密间隔的量子阱和/或其他氧化物异质结材料对响应的影响。这些研究促进了对新型光电紫外发光系统辐射复合的理解，这种辐射复合不是由体积、界面或表面性质定义的，而是由亚表面界面量子阱电子结构与表面化学吸附的耦合定义的。

Nontechnical Description: Next-generation devices require new classes of materials capable of advance (multi-) functional response. In this regard, complex-oxide materials and interfaces have the potential for far-reaching impact. Of particular interest are opportunities to harness novel light-matter interactions to enable a range of applications. Controlling such interactions requires exacting production of materials and in-depth understanding of the mechanism(s) underlying the phenomena. For example, semiconductor heterostructures drive optoelectronics for solid-state lighting, communications, computing, and sensing and the subsequent introduction of nitride- and simple oxide-based materials has helped pushed such technologies into the ultraviolet emission range. New functionalities involving ultraviolet-emitting devices may enable faster encoding and manipulation of information, new modes of chemical detection and sensing, and more efficient solid-state lighting. This project explores opportunities for on-demand complex oxide-electronics through local material reconfiguration. It builds upon discoveries of conductivity at the interface of two insulators, and demonstration of reversible, local manipulation of conductance to produce tunable ultraviolet-light emission from such materials. The project actively promotes the training of next-generation scientists and engineers in technologically important and relevant fields critical for the sustained economic vitality of the United States, focuses efforts on the mentoring and training of students from historically underrepresented groups, and provides research co-op and international research experiences for student trainees.Technical Description: In this project, a new optoelectronic materials paradigm is defined by the coupling of spatially- and chemically-selective chemisorption with sub-surface quantum well(s) formed at the interface(s) of two band insulators. Symmetry-breaking and electrostatic potential mismatch between constituent semiconductors at an interface results in novel phenomena inaccessible in the bulk. This emergent phenomena can, in some systems, be tuned extensively since a surface, and to some extent, an interface, is free to reconstruct structurally and electronically. Bringing a surface or sub-surface into equilibrium with a controlled environment enables local, reversible control of the electronic phase or functional state. The effects of adsorbate type and locality, of a symmetry-lowering field on the strength, energy, and spatial response of ultraviolet luminescence from one or more distinct sub-surface, two-dimensional electron liquid(s) exhibiting electron correlations are studied. In particular, the activities focus on understanding and ultimately controlling several distinguishing features: 1) how the steady-state ultraviolet light emission intensity changes in response to different adsorbates; 2) how the physical properties of the model system, as probed by changes in spectral emission, respond to externally applied fields; 3) how the ultraviolet luminescence, including locality and stability, can be controlled with external stimuli; and 4) what the introduction of multiple, closely-spaced quantum wells and/or other oxide heterojunction materials does to the response. These investigations advance understanding of radiative recombination in new model optoelectronic ultraviolet light-emitting systems defined not by bulk, interfacial or surface properties alone, but by coupling of sub-surface interfacial quantum well electronic structure to surface chemisorption.