Collaborative Research: Chemisorption-Induced Ultraviolet Quantum Well Optoelectronic Materials

非技术描述：下一代器械需要能够实现高级（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深远影响的潜力。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深入了解现象背后的机制。例如，半导体异质结构驱动用于固态照明、通信、计算和传感的光电子学，随后引入基于氮化物和简单氧化物的材料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以实现更快的信息编码和操作，新的化学检测和传感模式以及更有效的固态照明。该项目通过本地材料重新配置探索按需复杂氧化物电子产品的机会。它建立在两个绝缘体的界面处的导电性的发现的基础上，并且证明了可逆的、局部操纵导电性以从这些材料产生可调谐的紫外光发射。该项目积极促进对美国持续经济活力至关重要的技术重要性和相关领域的下一代科学家和工程师的培训，重点关注对历史上代表性不足的群体的学生的指导和培训，并为学生学员提供研究合作和国际研究经验。技术描述：在这个项目中，一个新的光电材料范例是通过空间和化学选择性化学吸附与形成在两个带绝缘体的界面处的亚表面量子阱的耦合来定义的。对称性破坏和静电势之间的不匹配的组成半导体在界面上的结果在体中无法访问的新现象。在某些系统中，这种涌现的现象可以被广泛地调整，因为表面，在某种程度上，界面，可以自由地在结构上和电子上重建。使表面或亚表面与受控环境平衡，使得能够局部可逆地控制电子相或功能状态。本文研究了吸附质类型和位置、磁场强度对一个或多个不同亚表面二维电子液体紫外发光强度、能量和空间响应的影响。特别是，这些活动侧重于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物而变化; 2）通过光谱发射的变化探测的模型系统的物理性质如何响应外部施加的场; 3）如何利用外部刺激来控制紫外发光，包括局部性和稳定性;以及4）引入多个紧密间隔的量子威尔斯和/或其它氧化物异质结材料对响应有什么影响。这些研究促进了对新型光电紫外发光系统中辐射复合的理解，该系统不仅由体、界面或表面性质定义，而且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。

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.