Film Stress and Morphology Evolution during MOCVD Growth of InGaN

技术：该项目探讨了在 Ga 极性和 N 极性 GaN 表面上通过金属有机化学气相沉积 (MOCVD) 生长 InGaN 过程中薄膜应力、表面形貌和微观结构的演变。将强调结合原位晶圆曲率测量来探测 MOCVD 生长期间双轴应力的动态变化和生长后透射电子显微镜表征。初步研究将重点研究 (0001) SiC 衬底上的 Ga 极性 GaN 上生长的 InGaN 的压缩应力松弛。该项目早期将研究富氮与富 III 族生长以及有意硅掺杂对材料的应力松弛、表面形态以及结构和光学性能的影响。然后将对在错误取向的 SiC 上生长的 N 极 InGaN/GaN 进行类似研究。该项目旨在识别和理解 InGaN 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，同时开发控制应力和减少缺陷形成的策略。非技术性：该项目解决材料科学主题领域的基础研究问题，以及电子和光子学的技术相关性。这项研究的结果预计将为 Ga 极性和 N 极性 InGaN 层的应力松弛和微结构演化机制提供新的见解，可用于改善光伏和固态照明性能。该项目构成了博士学位的基础。两名研究生的论文工作；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立大学 MRSEC 纳米科学中心的成员以及宾夕法尼亚州费城富兰克林研究所博物馆的人员合作，开发基于推车的能源材料交互式演示套件。 PI 将协助开发利用发光二极管传达技术概念的模块活动，例如半导体材料的发光、混色和固态照明。能源材料博物馆展览最初是为富兰克林研究所的参观者设计的，但也将在全国范围内至少二十个其他科学博物馆进行展示。

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.