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.

“该奖项的资金来源是《2009 年美国复苏和再投资法案》（公法 111-5）。”技术的。该项目致力于在整个成分范围内实现高晶体质量 InGaN 的外延生长。目的是更好地了解混溶间隙的特性，并探索能够持续提供单相 InGaN 薄膜的方法。理论研究表明，具有平行于c轴取向的界面的层（例如a面或m面InGaN）中的相分离被显着抑制。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。了解生长方向和应变对 InGaN 混溶间隙的基本影响的研究预计将带来一种实现单相器件质量 InGaN 外延层的新方法。这些薄膜将允许在以前无法达到的成分范围内研究 InGaN 的基本光学和传输特性。有关 InxGa1-xN 在混溶间隙区域 (0.45 x 0.75) 的光学和传输特性的详细研究还不可能，因为这些 InxGa1-xN 薄膜通常具有非常低的结晶质量，并且表现出微弱或可忽略不计的光致发光。预计混溶间隙区域中 InxGa1-xN 的许多重要物理性质（结构、光学和电学）将通过这些研究得到表征。非技术性。该项目解决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着的好处。 InGaN的带隙从约0.7 eV扩展到3.4 eV，覆盖了整个太阳光谱。原则上，基于不同In含量的多层InGaN的多结太阳能电池或光电化学电池能够高效地捕获穿过电池的不同波长的太阳光。 InGaN合金也可能是潜在重要的热电（TE）材料，并且可能是开发能够在新一代汽车中直接将热能直接转换为电能的TE发电机、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的其他材料的有吸引力的替代品。在先前预测的混溶间隙区域获得高质量的 InGaN 也将显着有利于波长超过 550 nm 的高效 LED 的开发。成功实现高效绿/黄 InGaN LED 将使白光 LED 技术能够通过 R-G-B 三色芯片集成方法实现，为普通照明提供高效光源。富 InGaN 的带隙也可以设计为与 1.5 微米左右的光纤通信波长相匹配。博士后和研究生将积极参与高度跨学科的研究项目，包括最先进的光子材料和结构外延研究到先进材料表征和微/纳米级原型光子/光电器件研究。本科生也将使用惠特克捐赠基金参与这项研究。教育和推广计划包括结合 TTU 工程推广中心开展的活动，开发向高中教师和学生团队展示“纳米光子学”的实践活动。