Dilute Nitride AlGaNP/GaP for Solid-State Lighting

用于固态照明的稀氮化物 AlGaNP/GaP

• 批准号: 0606389
• 负责人: Charles Tu
• 金额: $ 32.11万
• 依托单位: University of California-San Diego
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-07-01 至 2009-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0606389&HistoricalAwards=false
• 关键词: Dilute; Nitride; AlGaNP; GaP; Solid

Technical: This project aims for greater fundamental understanding and improved quantum efficiency of solid state light emitters in the green-to-amber spectral region (~540 nm to ~610 nm wavelength). The approach involves investigating the material system, AlGaNP grown on GaP, with outcomes anticipated of better material properties and simpler processing technologies for solid state lighting. The approach consists of three parts: investigation of fundamental materials science issues involved in the growth, processing, and optimization of amber emitting GaNP/GaP LEDs, comparison with AlInGaP/GaAs LEDs, exploring AlGaNP/GaP for green emission, and fabricating green emitting AlGaNP/AlGaP LEDs and comparing with InGaN/GaN LEDs. Relevant physical properties, such as effective mass, band alignment, and optical properties, will be systematically investigated. It is well known that the quantum efficiency of InGaN LEDs decreases as the wavelength increases from blue to green because material quality degrades as the In concentration increases. The quantum efficiency of AlInGaP LEDs decreases as the wavelength decreases from red to amber because the band alignment approaches a type II, staircase lineup, resulting in reduced luminescence intensity. With theoretical guidance, the material system, AlGaNP-on-GaP, was chosen for LEDs emitting in this "color gap" region because of its potential advantages: 1) maximum light extraction because of an all-transparent layer structure, except the active region, on a transparent GaP substrate; 2) low threading dislocation density expected because of a lattice-matched, or pseudomorphic, structure on a GaP substrate, in contrast to lattice-mismatched InGaN/GaN on sapphire or SiC; 3) a substrate (GaP) with higher thermal conductivity than sapphire and GaAs (1.1 vs. 0.35 and 0.55 W cm-1 K-1, respectively); 4) better high-temperature characteristics because of stronger carrier confinement from larger conduction-band and valence-band offset, which are 3 times those of AlInGaP/AlInP; 5) higher yield and lower cost because a smaller size is needed for the same power (chips can be made smaller and the yield per wafer increased, reducing cost per chip); 6) simpler, cost-effective one-step epitaxy, instead of substrate removal and wafer bonding needed for AlInGaP LEDs, or heteroepitaxial growth of InGaN/GaN on sapphire or SiC.Non-Technical: The project addresses basic research issues in a topical area of materials science having high technological relevance. The research will contribute basic materials science knowledge at a fundamental level to new understanding and capabilities in electronic devices. An important feature of the program is the integration of research and education through the training of students in a fundamentally and technologically significant area. The research activities will promote interdisciplinary training of graduate students in growth and characterization of novel compound semiconductors, LED device design, fabrication and testing, and provide training in preparation of written and oral presentations. Undergraduate students will be recruited from sources such as the McNair Program, which serves low-income students and/or underrepresented minorities. Undergraduate students will have the opportunity to work on advanced characterizations, such as atomic force microscopy, and participate in undergraduate research conferences at UCSD. Additionally, the PI will participate in the COSMOS (California State Summer School for Mathematics and Science) residential summer program, where a team of high school students will participate in an LED project using commercial LEDs and those fabricated in this program for solid-state lighting experiments..

技术：该项目的目的是在绿色至木材光谱区域（〜540 nm至〜610 nm波长）中具有更大的基本理解和提高固态发射器的量子效率。该方法涉及研究材料系统，即在间隙上生长的Alganp，结果预计有更好的材料特性和更简单的固态照明处理技术。该方法包括三个部分：研究琥珀色发射GANP/GAP LED的生长，加工和优化的基本材料科学问题，与Alingap/GaAS LED进行比较，探索绿色排放的Alganp/Gap，以及制造绿色发射Alganp/Algap LED和与Ingan/Gan LED进行比较。相关的物理特性，例如有效的质量，带对准和光学特性，将被系统地研究。众所周知，随着波长从蓝色增加到绿色，INGAN LED的量子效率降低，因为材料质量随着浓度的增加而降低。随着波长从红色到琥珀的降低，Alingap LED的量子效率降低，因为频带比对接近II型，楼梯阵容，从而降低了发光强度。通过理论指导，由于其潜在的优势，选择了在此“颜色差距”区域发射的LED的材料系统Alganp-on-pap：1）由于在透明的差距底物上，由于具有全透明区域的全透明层结构，因此最大的光提取。 2）与缝隙基板上的晶格匹配或伪形的结构，预期的低螺纹脱位密度与蓝宝石或SIC上的晶格不匹配的Ingan/gan相反； 3）与蓝宝石和GAAS的导热率更高的底物（GAP）（分别为1.1 vs. 0.35和0.55 W CM-1 K-1）； 4）更好的高温特性，因为较大的传导带和价循环偏移量更强，这是Alingap/Alinp的3倍； 5）较高的产量和较低的成本，因为相同功率需要较小的尺寸（可以使芯片更小，并且每晶片的产量增加，从而降低每芯片的成本）； 6）更简单，具有成本效益的一步外观，而不是Alingap LED所需的底物和晶圆粘结，或者在蓝宝石或SIC.Non-Technical上INGAN/GAN的杂次增长。该研究将在基本层面上为电子设备的新理解和能力提供基本材料的知识。该计划的一个重要特征是通过培训学生在根本和技术意义上的领域中培训研究和教育。研究活动将促进研究生在新型复合半导体，LED设备设计，制造和测试的成长和表征方面的跨学科培训，并提供培训，以准备书面和口头表现。本科生将从诸如McNair计划之类的来源招募，该计划为低收入学生和/或代表性不足的少数群体提供服务。本科生将有机会进行高级特征，例如原子力显微镜，并参加UCSD的本科研究会议。此外，PI将参加Cosmos（加利福尼亚州立大学数学和科学暑期学校）住宅夏季计划，其中一组高中生将使用商业LED和该计划中的固态照明实验制造的LED参与LED项目。