Tailoring Surface Morphology in Group III Nitride Heteroepitaxy

该项目旨在涵盖氮化镓薄膜生长的完整周期，从衬底制备到缓冲层和氮化物涂层的生长，再到金属接触层的沉积。主要目的是利用原位显微观察提供的直接反馈，通过MBE实现光滑的二维基面取向III族氮化物层的一致生长，并在生长过程中对表面形貌进行定制、优化和控制。超高真空（UHV）显微镜、低能电子显微镜（LEEM）、扫描隧道显微镜（STM）和原子力显微镜（AFM）的组合将用于在6H-SiC（0001）衬底上进行III族氮化物的原位沉积和生长研究。SiC被选为衬底而不是蓝宝石，因为它的半导体性质提供了顶部和背面的接触，这不仅更方便我们提出的原位显微镜研究，而且用于器件应用。通过对生长过程的更深入的了解，将建立更可行的MBE连续生长III族氮化物光滑二维基面取向层的指导方针。该项目涉及材料科学中具有高技术相关性的主题领域的基础研究问题。现在有了实验工具，可以在原子水平上观察基本的表面过程，这些过程一旦得到更好的理解，就会促进基础科学和技术的进步。从研究中获得的基本知识和理解预计将有助于提高先进器件和电路的性能和稳定性，为设计和生产改进的材料和材料组合提供基本的理解和基础。该计划的一个重要特点是通过在基础和技术重要领域培养学生，将研究和教育相结合

This project aims to encompass the complete cycle of film growth of GaN, from substrate preparation through growth of buffer layers and nitride epilayers to deposition of metal contact layers. The primary objective is to achieve consistent growth of smooth two-dimensional basal-plane oriented layers of Group III nitrides by MBE using direct feedback provided by in-situ microscopic observations, and to tailor, optimize, and control the surface morphology during growth. A combination of ultrahigh vacuum (UHV) microscopies: low-energy electron microscopy (LEEM), scanning tunneling microscope (STM), and atomic force microscopy (AFM) will be used to conduct in situ deposition and growth studies of Group III nitrides on 6H-SiC(0001) substrates. SiC is chosen as the substrate over sapphire because of its semiconducting nature offering topside and backside contacts, which is not only more convenient for our proposed in situ microscopy studies but also for device applications. Through greater understanding of the growth process, more viable guidelines to the consistent growth of smooth two-dimensional basal-plane oriented layers of Group III nitrides by MBE will be established.%%%The project addresses basic research issues in a topical area of materials science with high technological relevance. Experimental tools are now available to allow atomic level observation of elementary surface processes which when better understood allow advances in fundamental science and technology. The basic knowledge and understanding gained from the research is expected to contribute to improving the perform-ance and stability of advanced devices and circuits by providing a fundamental understanding and a basis for designing and producing improved materials, and materials combinations. 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.***