Growth of Low Defect Density III-Nitride Compounds on Nanowires

低缺陷密度 III 族氮化物在纳米线上的生长

• 批准号: 1105842
• 负责人: S. Bedair
• 金额: $ 37.58万
• 依托单位: North Carolina 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: 2011-09-15 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1105842&HistoricalAwards=false
• 关键词: Growth; Low; Defect; Density; III

NON-TECHNICAL DESCRIPTION: Gallium nitride optoelectronic devices are amongst the fastest expanding fields and are being extensively used in solid-state lighting, optical imaging, scanners, power amplifiers and switches for interfacing renewable energy with the electric grid. Therefore, their importance is of the utmost concern. Efforts to successfully improve the material's quality will enhance device performance and impact several industrial and consumer products.TECHNICAL DETAILS: III-Nitride compounds are the material of choice in several optical and electronic devices. High defect densities (approximately 10exp9 to 10exp10 /cm2) are currently present in III-Nitride compounds due to the lack of both lattice matched substrates and lattice matched multilayers made from binary and ternary compounds. These defects act as non-radiative recombination and scattering centers that, for example, impact minority carrier lifetime and reduce thermal conductivity. These high defect densities limit the performance and reliability of several optoelectronic devices such as ultraviolet (UV) light-emitting diodes (LEDs), laser diodes as well as power devices and switches. Previous efforts to reduce these defects have had limited success. The objective of this project is to achieve films in III-nitride compounds with defect densities lower than 10exp7/cm2 over the entire wafer. The overall approach is involves overgrow from nanostructured GaN templates by using an innovative approach. It begins with a mask-less fabrication of nanowires with conical tips to facilitate the growth and coalescence of the overgrown GaN film. GaN three-dimensional growth on different crystallographic facets in early overgrowth stages on nanowire structures plays a key role in the remaining dislocation interactions (since the likelihood for dislocation annihilation and formation of dislocation loops are greatly increased). Subsequently a network of embedded voids in the epitaxial films are generated that act as dislocation sinks. Studies are underway to determine the dominant mechanism in the defects reduction. During the course of this project, both undergraduate and graduate students are engaged in the research. As well, the outreach program includes undergraduates, minority students, and high school teachers.

非技术描述：氮化镓光电子器件是发展最快的领域之一，被广泛应用于固态照明、光学成像、扫描仪、功率放大器和用于可再生能源与电网接口的开关。因此，它们的重要性是最令人关注的。成功提高材料质量的努力将提高设备性能，并影响几种工业和消费产品。技术细节：III-氮化物化合物是几种光学和电子设备的首选材料。由于缺乏晶格匹配衬底和由二元和三元化合物制成的晶格匹配多层膜，III-氮化物中目前存在高缺陷密度(约10exp9到10exp10/cm2)。这些缺陷起到非辐射复合和散射中心的作用，例如，影响少数载流子寿命并降低热导率。这些高缺陷密度限制了几种光电子器件的性能和可靠性，例如紫外线发光二极管(LED)、激光二极管以及功率器件和开关。之前减少这些缺陷的努力收效甚微。该项目的目标是在整个晶片上实现缺陷密度低于10exp7/cm2的III-氮化物薄膜。总体方法是使用一种创新方法从纳米结构GaN模板过度生长。它从无掩模的纳米线制造开始，带有圆锥形尖端，以促进过度生长的GaN薄膜的生长和结合。在纳米线结构的早期过度生长阶段，GaN在不同晶面上的三维生长在剩余的位错相互作用中起着关键作用(因为位错湮灭和位错环形成的可能性大大增加)。随后，在外延薄膜中产生嵌入空穴的网络，其作用是位错槽。目前正在进行研究，以确定缺陷减少的主要机制。在这个项目的过程中，本科生和研究生都在从事这项研究。此外，外展计划还包括本科生、少数族裔学生和高中教师。