Contact Formation to Gallium Nitride: Interfacial Chemistry, Structure and Properties

这个GOALI项目代表了威斯康星大学和惠普实验室的研究人员之间的合作努力，以解决GaN欧姆接触的基础材料科学问题。本项目综合研究了金属/氮化镓界面的热力学和动力学稳定性以及n型和p型氮化镓的输运行为等基本问题。广泛的电学和冶金特性将在使用选定的金属化作为模型系统制造的退火金属/氮化镓触点上进行。电气特性将包括电流电压（I-V）和电容电压（C-V）测量，以确定诸如特定接触电阻，肖特基或接触势垒高度的大小以及表面附近空间电荷区域的变化等特性。反应界面的冶金表征将使用多种技术进行，如SAM， XRD， TEM， HRTEM， SIMS和RBS。为了解决接触形成的初始阶段，将利用同步辐射的x射线光电发射光谱（XPS）来检查界面的演变。基于xps的金属/氮化镓研究将补充更广泛的大块薄膜表征。这些联合研究有望提供对金属/氮化镓界面的深入了解，并为开发金属化氮化半导体器件提供关键信息。该项目涉及具有高潜在技术相关性的材料科学主题领域的基础研究问题。该研究将为电子/光子器件的重要制造方面提供基础材料科学知识。现在可以使用新的实验材料科学和光学工具来更详细地观察基本的表面/界面过程，当更好地理解这些过程时，可以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有望有助于提高用于计算和通信的先进设备和电路的性能和稳定性。该计划的一个重要特点是通过培养学生在一个基础和技术上重要的领域的研究和教育的整合。该项目由DMR/电子材料计划和MPS OMA（多学科活动办公室）共同支持

This GOALI project represents a collaborative effort between researchers at the U. of Wisconsin and Hewlett-Packard Laboratories to address fundamental materials science issues in ohmic contacts to GaN. The project takes a comprehensive approach to study basic issues concerning the thermodynamic and kinetic stability at metal/GaN interfaces as well as the transport behavior for both n- and p-type GaN. Extensive electrical and metallurgical characterization will be performed on annealed metal/GaN contacts fabricated using selected metallizations as model systems. The electrical characterization will include current-voltage (I-V) and capacitance-voltage (C-V) measurements to determine such properties as the specific contact resistance, the magnitude of the Schottky or contact barrier height, and the changes in the space charge region near the surface. Metallurgical characterization of the reacted interfaces will be performed using a variety of techniques such as SAM, XRD, TEM, HRTEM, SIMS and RBS. To address initial stages of contact formation, the evolution of interfaces will be examined by x-ray photoemission spectroscopy (XPS), utilizing synchrotron radiation. The XPS-based studies on metal/GaN will complement the more extensive characterization of the bulk thin films. The combined studies are expected to provide insight into metal/GaN interfaces not currently available and furnish information critical for development of metallizations to nitride based semiconductor devices.%%%The project addresses basic research issues in a topical area of materials science having high potential technological relevance. The research will contribute basic materials science knowledge at a fundamental level to important fabrication aspects of electronic/photonic devices. New experimental materials science and optical tools are now available to allow more detailed observation of elementary surface/interface 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 performance and stability of advanced devices and circuits for computing and communications. 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. The project is co-supported by the DMR/Electronic Materials program and the MPS OMA(Office of Multidisciplinary Activities).***