Bridging the Miscibility Gap in InGaN Alloys

缩小 InGaN 合金的混溶性差距

• 批准号: 0906879
• 负责人: Jingyu Lin
• 金额: $ 47.52万
• 依托单位: Texas Tech University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-07-01 至 2013-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0906879&HistoricalAwards=false
• 关键词: Bridging; Miscibility; Gap; InGaN; Alloys

"This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5)." Technical. This project addresses the epitaxial growth of high crystalline quality InGaN across the complete composition range. The aim is to gain greater understanding of the properties of the miscibility gap and to explore methods that can consistently provide single phase InGaN films. Theoretical studies suggest that phase separation in layers having the interface oriented parallel to the c-axis (such as a- or m-plane InGaN) is dramatically suppressed. Thus, the approach is to develop MOCVD processes for the growth of InGaN epilayers on a-plane through different epilayer templates (AlN, GaN, and InN). Studies to understand fundamental effects of growth orientation and strain on the miscibility gap in InGaN are expected to lead to a new approach for achieving single phase device quality InGaN epilayers. These films will then allow for studies of fundamental optical and transport properties of InGaN in composition ranges which were previously inaccessible. Detailed studies concerning the optical and transport properties of InxGa1-xN in the miscibility gap region (0.45 x 0.75) have not been possible because these InxGa1-xN films generally have been of very low crystalline quality and exhibit weak or negligible photoluminescence. It is anticipated that many of the important physical properties (structural, optical, and electrical) of InxGa1-xN in the miscibility gap region will be characterized through these studies. Non-Technical. The project addresses fundamental research issues in a topical area of electronic/photonic materials science having technological relevance. The realization of device quality InGaN epilayers over a more complete alloy range would yield significant benefits for many III-nitride based optoelectronic devices. The bandgap of InGaN expands from about 0.7 eV to 3.4 eV, which covers the entire solar spectrum. In principle, a multijunction solar cell or photoelectrochemical cell based on multi-layers of InGaN with different In-contents is highly efficient at capturing different wavelengths of the sunlight passing through the cell. InGaN alloys could also be potentially important thermoelectric (TE) materials and may be an attractive alternative to other materials for the development of TE generators that are able to directly convert heat to electricity in new generation automobiles, radioisotope TE generators in spacecraft or cooling modules for enhanced efficiency and lifetime of micro/nano-scale sensor networks. Attainment of high quality InGaN in the previously predicted miscibility gap region would also significantly benefit the development of high efficiency LEDs with wavelengths longer than 550 nm. The successful attainment of highly efficient green/yellow InGaN LEDs would then enable the technology for white LEDs through the R-G-B three color chip integration approach providing highly efficient light sources for general illumination. The bandgap of In-rich InGaN could also be engineered to match the fiber optic communication wavelength around 1.5 um. Postdoctoral and graduate students will be actively involved in a research program that is highly interdisciplinary in nature including state-of-the-art epitaxial research of photonic materials and structures to advanced materials characterization and micro/nano-scale prototype photonic/optoelectronic device research. Undergraduates will also participate in this research using Whitacre Endowment funds. Plans for education and outreach include the development of hands-on activities to be presented to teams of high school teachers and students on 'Nanophotonics' in conjunction with activities conducted by the Center of Engineering Outreach at TTU.

“该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。“技术性的。该项目致力于在整个成分范围内外延生长高结晶质量的InGaN。其目的是获得更好的理解的性能的可扩展性差距，并探索方法，可以始终提供单相InGaN薄膜。理论研究表明，具有平行于c轴取向的界面的层（例如a-或m-平面InGaN）中的相分离被显著抑制。因此，该方法是开发MOCVD工艺，通过不同的外延层模板（AlN，GaN和InN）在a平面上生长InGaN外延层。了解生长取向和应变对InGaN外延层的基本影响的研究有望为实现单相器件质量的InGaN外延层提供一种新的方法。然后，这些薄膜将允许InGaN的基本光学和输运性质的组成范围内，这是以前无法访问的研究。关于InxGa 1-xN在可伸缩间隙区域（0.45 × 0.75）中的光学和输运性质的详细研究是不可能的，因为这些InxGa 1-xN膜通常具有非常低的结晶质量并且表现出弱的或可忽略的光致发光。预计InxGa 1-xN在可兼容性间隙区域中的许多重要物理性质（结构、光学和电学）将通过这些研究来表征。非技术性。该项目解决了具有技术相关性的电子/光子材料科学主题领域的基础研究问题。在更完整的合金范围内实现器件质量的InGaN外延层将为许多基于III族氮化物的光电器件带来显著的益处。InGaN的带隙从约0.7 eV扩展到3.4 eV，其覆盖整个太阳光谱。原则上，基于具有不同In含量的InGaN多层的多结太阳能电池或光电化学电池在捕获穿过电池的不同波长的太阳光方面是高效的。InGaN合金也可能是潜在的重要热电（TE）材料，并且可能是开发TE发电机的其他材料的有吸引力的替代品，TE发电机能够在新一代汽车中直接将热量转换为电力，航天器中的放射性同位素TE发电机或冷却模块，以提高微/纳米级传感器网络的效率和寿命。在先前预测的可扩散性间隙区域中获得高质量InGaN也将显著有益于波长长于550 nm的高效率LED的开发。高效绿色/黄色InGaN LED的成功实现则将通过R-G-B三色芯片集成方法实现用于白色LED的技术，从而为一般照明提供高效光源。富In InGaN的带隙也可以被设计为与1.5 μ m左右的光纤通信波长相匹配。博士后和研究生将积极参与一个高度跨学科的研究项目，包括光子材料和结构的最先进的外延研究，先进的材料表征和微/纳米级原型光子/光电器件研究。本科生也将参加这项研究使用惠塔克捐赠基金。教育和推广计划包括开发实践活动，向高中教师和学生团队介绍“纳米光子学”，并与TTU工程推广中心开展的活动相结合。