Film Stress and Morphology Evolution during MOCVD Growth of InGaN

技术：本项目探索了金属有机化学气相沉积(MOCVD)在GaN和N极GaN表面上生长InGaN过程中薄膜应力、表面形貌和微结构的演变。本课程将重点结合晶片曲率的现场测量，以探测MOCVD生长过程中双轴应力的动态变化，以及生长后的透射电子显微镜表征。最初的研究将集中在(0001)碳化硅衬底上生长在GaN上的InGaN的压应力松弛。富N和富III族生长和有意的掺硅对材料的应力松弛、表面形态以及结构和光学性质的影响将在项目初期进行研究。然后，将对在错误取向的碳化硅上生长的N-极性InGaN/GaN进行可比性研究。该项目旨在确定和了解InGaN中应力松弛的基本机制，以及由此产生的缺陷的类型和空间分布，以及制定控制应力和减少缺陷形成的策略。非技术性：该项目解决与电子和光子学技术相关的材料科学专题领域的基础研究问题。这项研究的结果有望对Ga极和N极InGaN层的应力松弛和微结构演化机制提供新的见解，这些机制可用于改善光伏和固态照明性能。该项目构成了两名研究生的博士论文工作的基础；本科生也将通过宾夕法尼亚州立大学的REU项目参与研究。该项目使PI和她的研究生能够与宾夕法尼亚州费城富兰克林研究所博物馆的宾夕法尼亚州立大学纳米科学和人员MRSEC中心的成员合作，开发基于购物车的能源材料互动演示套件。PI将协助开发利用发光二极管来传达技术概念的模块活动，如半导体材料的发光、颜色混合和固态照明。博物馆关于能源材料的展览最初将为富兰克林研究所的参观者制作，但也将在全国范围内分发给至少20家其他科学博物馆。

Technical: This project explores the evolution of film stress, surface morphology and microstructure during the growth of InGaN by metalorganic chemical vapor deposition (MOCVD) on Ga-polar and N-polar GaN surfaces. A combination of in-situ wafer curvature measurements to probe dynamic changes in biaxial stress during MOCVD growth and post-growth transmission electron microscopy characterization will be emphasized. Initial studies will focus on investigation of compressive stress relaxation in InGaN grown on Ga-polar GaN on (0001) SiC substrates. The effects of N-rich vs group III-rich growth and intentional Si doping on stress relaxation, surface morphology and the structural and optical properties of the material will be studied early in the project. Comparable studies will then be carried out for N-polar InGaN/GaN grown on misoriented SiC. The project aims for identification and understanding of fundamental mechanisms of stress relaxation in InGaN, and the type and spatial distribution of resulting defects along with development of strategies to control stress and reduce defect formation. Non-technical: The project addresses basic research issues in a topical area of materials science with technological relevance in electronics and photonics. The results from the proposed study are anticipated to yield new insights into the mechanisms of stress relaxation and microstructure evolution in Ga-polar and N-polar InGaN layers that can be exploited for improvements in photovoltaic and solid state lighting performance. The project forms the basis of Ph.D. thesis work of two graduate students; undergraduate students will also be involved in the research through REU programs at Penn State. The project enables the PI and her graduate students to collaborate with members of the Penn State MRSEC Center for Nanoscale Science and personnel at the Franklin Institute Museum in Philadelphia, PA on the development of a cart-based interactive demonstration kit on energy materials. The PI will assist in the development of module activities that utilize light emitting diodes to convey technical concepts such as light emission from semiconductor materials, color mixing and solid state lighting. The museum show on energy materials will initially be developed for visitors of the Franklin Institute but will also be distributed nationwide to at least twenty other science museums.