Tailoring Surface Morphology in Group III Nitride Heteroepitaxy

该项目旨在涵盖GaN薄膜生长的整个周期，从衬底制备到缓冲层和氮化物外延层的生长，再到金属接触层的沉积。其主要目标是通过分子束外延技术，利用原位显微观察提供的直接反馈，实现均匀的二维基面取向的III族氮化物层的一致生长，并在生长过程中调整、优化和控制表面形貌。超高真空(UHV)显微镜的组合：低能电子显微镜(LEEM)、扫描隧道显微镜(STM)和原子力显微镜(AFM)将用于在6H-SiC(0001)衬底上原位沉积和生长III族氮化物。选择碳化硅作为衬底而不是蓝宝石，是因为它的半导体性质提供了正面和背面的接触，这不仅对我们提出的原位显微镜研究更方便，而且对器件应用也更方便。通过更好地了解生长过程，将建立更可行的指导方针，通过分子束外延连续生长光滑的III族氮化物的二维基面取向的层。%该项目解决具有高度技术相关性的材料科学主题领域的基础研究问题。现在可以使用实验工具对基本的表面过程进行原子水平的观察，如果更好地了解这些过程，就可以推动基础科学和技术的进步。从研究中获得的基本知识和理解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认识和基础。该计划的一个重要特点是通过在一个具有根本意义和技术意义的领域对学生进行培训，将研究和教育结合起来。

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.***