Collaborative Research: Chemisorption-Induced Ultraviolet Quantum Well Optoelectronic Materials

非技术描述：下一代设备需要能够先进(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颖的光-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的机制的深入理解(S)。例如，半导体异质结驱动光电子学用于固态照明、通信、计算和传感，随后氮化物和简单氧化物材料的引入有助于将这些技术推向紫外线发射范围。涉及紫外线发射设备的新功能可能会使信息的编码和处理更快，化学检测和传感的新模式，以及更高效的固态照明。该项目探索了通过本地材料重新配置来实现按需复杂氧化物电子产品的机会。它建立在两个绝缘体界面传导性的发现基础上，并展示了可逆的局部电导操纵，以从此类材料产生可调的紫外光发射。该项目积极促进下一代科学家和工程师在对美国持续经济活力至关重要的重要技术和相关领域的培养，重点关注对来自历史上代表性不足的群体的学生的指导和培训，并为学生培训提供研究合作和国际研究经验。技术描述：在该项目中，通过空间和化学选择性化学吸附与在两个带绝缘体的界面(S)形成的亚表面量子井(S)的耦合，定义了一种新的光电材料范式。界面处组成半导体之间的对称性破坏和静电势不匹配导致了无法在整体上实现的新现象。在一些系统中，这种新出现的现象可以被广泛地调谐，因为表面，在某种程度上，界面，可以自由地从结构和电子上重建。使表面或亚表面与受控环境达到平衡，可以对电子相或功能状态进行局部可逆控制。研究了对称性降低场的吸附类型和位置对具有电子关联的一个或多个不同亚表面二维电子液体(S)的紫外发光强度、能量和空间响应的影响。特别是，这些活动集中于了解并最终控制几个明显的特征：1)稳态紫外光发射强度如何随着不同的吸附而变化；2)通过光谱发射的变化来探测模型系统的物理性质如何响应外部场；3)紫外线发光，包括局部性和稳定性，如何可以随着外部刺激而被控制；以及4)多个紧密间隔的量子井和/或其他氧化物异质结材料的引入对响应有什么影响。这些研究促进了人们对新型光电紫外光发射系统中辐射复合的理解，这些复合不是由体、界面或表面性质定义的，而是通过亚表面界面量子阱电子结构与表面化学吸附的耦合来定义的。

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.