Charge and Currrent Imaging of GaN Devices

这个项目的目标是获得基本的了解，最终降低GaN基器件的性能的充电缺陷和泄漏路径。这种缺陷可能来自于体缺陷，例如穿透位错和反转域，或者来自于由于钝化不良而导致的表面状态。该方法包括HVPE（氢化物气相外延）GaN薄膜生长蓝宝石，SiC和GaN模板，然后通过表面科学表征，重点是使用表面接触电位电力显微镜（SCP-EFM）和导电原子力显微镜（C-AFM）等技术在微米至纳米尺度上成像缺陷特征。该项目将扩展基于AlGaN/GaN异质结构的有源调制掺杂场效应晶体管（MODFET或HEMT）的成像。这些成像技术将有助于阐明表面缺陷、应变和极化如何与器件异常（如降低高频性能的电流滞后）相关。还将探讨表面钝化技术和界面障碍的影响。这些发现将增强对电流传导和电荷转移的寄生途径的理解，也将适用于其他GaN器件，并将扩展对这一重要材料系统的基本理解。该项目的广泛影响包括沿着对研究生和本科生进行多学科研究的培训，推动高技术影响研究领域的发展。PI来自电气工程和物理系，将利用他们在表面科学成像方面的专业知识来解决MODFET结构中的电活性缺陷的基本问题，以及制造和测试原型器件结构。该项目为研究生和本科生提供支持，他们将有独特的研究和教育机会，使用复杂的材料合成，加工和表征设备沿着设备制造，测试和分析，同时在材料科学，物理学和电气工程的联合指导环境中参与跨学科研究。***

The goal of this project is to gain fundamental understanding of charged defects and leakage paths that ultimately degrade performance in GaN-based devices. Such defects may arise from bulk imperfections such as threading dislocations and inversion domains, or from surface states due to poor passivation. The approach includes HVPE (hydride vapor phase epitaxy) GaN film growth on sapphire, SiC, and GaN templates followed by surface science characterization with an emphasis on imaging defect features on a micron to nanometer-scale using techniques such as Surface-Contact-Potential Electric Force Microscopy (SCP-EFM) and Conductive Atomic Force Microscopy (C-AFM). The project will extend the imaging of active Modulation Doped Field Effect Transistors (MODFET's or HEMT's) based on AlGaN/GaN heterostructures. These imaging techniques will help elucidate how surface defects, strain, and polarization are related to device anomalies such as current lag that degrade high frequency behavior. The influence of surface passivation techniques and interface barriers will also be explored. These findings, which will enhance understanding of parasitic pathways to current conduction and charge transfer, will also be applicable to other GaN devices and will extend fundamental understanding of this important materials system. %%% The broad impact of this project includes advancement of a high technological impact research area along with training of graduate and undergraduate students in multidisciplinary research. The PI's are from departments of Electrical Engineering and Physics, and will collaboratively use their expertise in surface science imaging to address fundamental problems of electrically active defects in MODFET structures, as well as to fabricate and test prototype device structures. The project provides support for graduate and undergraduate students who will have unique research and educational opportunities working with sophisticated materials synthesis, processing, and characterization equipment along with device fabrication, testing, and analysis, while participating in interdisciplinary research in an environment of joint mentoring across materials science, physics, and electrical engineering. ***