CAREER: Extreme band engineering in polarization graded nanowire heterostructures for high efficiency photonics

职业：用于高效光子学的偏振梯度纳米线异质结构的极带工程

• 批准号: 1055164
• 负责人: Roberto Myers
• 金额: $ 53万
• 依托单位: Ohio State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-07-15 至 2016-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1055164&HistoricalAwards=false
• 关键词: CAREER; Extreme; band; engineering; polarization

Technical: This project will advance the academic and public understanding of the principles of optical/electronic materials used for photonics through laboratory research and educational outreach. Wide bandgap III-Nitride semiconductors span the ultraviolet-visible-near infrared spectrum finding energy efficient applications in ultraviolet-visible light sources and detectors. Self-assembled Nitride nanowires increase the design flexibility in heterostructures due to high tolerance to lattice mismatch. This project will achieve new types of optical and electrical functionality in nanowire heterostructures for advanced high efficiency photonics. In bulk, polarization charge and bandgaps in GaN, AlN, and InN cannot be maintained in a single heterostructure without generating large numbers of dislocations due to strain relaxation. Nanowires sidestep the constraint of epitaxial strain making possible extreme energy landscapes for electrons and holes in graded AlGaN and InGaN heterostructures, while maintaining single crystal defect-free active regions. A remarkable array of heterostructures are possible exhibiting large built-in electric fields due to polarization charge that separate electrons and holes with high speed and efficiency, properties that enable high speed photodetectors covering a broad range in energy. Polarization grading will also be used to achieve impurity free p and n type doping in nanowires, which sidesteps the problem of impurity doping in nanostructures, and will be used to demonstrate a dopant-free pn-junction LED. To achieve these heterostructures, a systematic mapping of the growth phase diagram of molecular beam epitaxy growth of self-assembled GaN and InN nanowires on Si (111) for arbitrary selection of nanowire diameter and density will be investigated, and a suite of structural, optical, and electronic techniques will be employed, including SEM, Z-contrast TEM, XRD, time-resolved photoluminescence, electroluminescence, nanowire transport, and trap spectroscopy to examine fundamental transport and optical properties as they relate to nanowire structure and polarization charge/doping phenomena.NonTechnical: Controlling how atoms combine to form nanoscale crystals of semiconductors allows efficient conversion of light to electricity, and vice versa. However, even scientifically inclined students and teachers are largely unaware of the foundations of remarkable solar conversion, lighting, and display technologies, and completely unaware of the science of crystal growth. To address this shortfall, tutorials and lab demonstrations geared toward high school students will be integrated into the extensive outreach infrastructure at Ohio State, including open houses and summer camps that target minority students and women. A series of day long and summer camp events in the department of Materials Science and Engineering will take part in a hands-on tutorial/lab demonstration on materials for electro-optical energy conversion. The same tutorial will be remotely beamed to high school students around the country through the Electronics Experts program at the COSI science museum, which also provides a framework for tutorial development, and evaluation.

技术：该项目将通过实验室研究和教育推广，促进学术界和公众对用于光子学的光学/电子材料原理的理解。宽带隙 III 族氮化物半导体跨越紫外-可见-近红外光谱，在紫外-可见光源和探测器中找到节能应用。由于对晶格失配的高容忍度，自组装氮化物纳米线提高了异质结构的设计灵活性。该项目将在纳米线异质结构中实现新型光学和电学功能，以实现先进的高效光子学。在体中，GaN、AlN 和 InN 中的极化电荷和带隙不能在单个异质结构中保持，而不因应变弛豫而产生大量位错。纳米线避开了外延应变的限制，使渐变 AlGaN 和 InGaN 异质结构中的电子和空穴的极端能量景观成为可能，同时保持单晶无缺陷有源区。由于极化电荷能够高速高效地分离电子和空穴，因此一系列引人注目的异质结构可能表现出大的内置电场，这些特性使高速光电探测器能够覆盖广泛的能量范围。偏振分级还将用于实现纳米线中的无杂质 p 和 n 型掺杂，从而回避纳米结构中的杂质掺杂问题，并将用于演示无掺杂剂 pn 结 LED。为了实现这些异质结构，将研究在 Si（111）上自组装 GaN 和 InN 纳米线的分子束外延生长的生长相图的系统映射，以任意选择纳米线直径和密度，并研究一套结构、光学，并将采用电子技术，包括 SEM、Z 衬度 TEM、XRD、时间分辨光致发光、电致发光、纳米线传输和陷阱光谱，以检查与相关的基本传输和光学特性。纳米线结构和极化电荷/掺杂现象。非技术：控制原子如何结合形成半导体纳米级晶体可以实现光与电的有效转换，反之亦然。然而，即使是有科学倾向的学生和教师也基本上不了解卓越的太阳能转换、照明和显示技术的基础，并且完全不了解晶体生长的科学。为了解决这一不足，针对高中生的教程和实验室演示将被纳入俄亥俄州立大学广泛的外展基础设施中，包括针对少数族裔学生和女性的开放日和夏令营。材料科学与工程系的一系列为期一天的夏令营活动将参与电光能量转换材料的实践教程/实验室演示。同样的教程将通过 COSI 科学博物馆的电子专家项目远程传输给全国各地的高中生，该项目还提供了教程开发和评估的框架。