EAGER: A Novel GaN/AlGaN Nanostructure Room-Temperature Sensor for Security Applications

概述：近年来，太赫兹技术引起了人们的极大兴趣，因为太赫兹射线是非电离的，并且在安全检查，国土安全，射电天文学，制造业，通信和生物传感方面具有吸引人的应用。 拟议的研究将证明GaN/AlGaN核/壳纳米结构为基础的多沟道场效应晶体管（FET）阵列的可行性，用于感测太赫兹（THz）辐射在0.5至5 THz的范围内使用等离子体激发的二维电子气在这种结构。 通过使用新颖的设计和制造策略，具有改进的等离子体波速度和频率的高电子气密度是可行的，这将确保这些探测器在室温下操作。这项基础研究的广泛目标有两个方面：1）在室温下观察具有良好品质因数和频率可调谐性的谐振检测; 2）开发一种设计策略，用于演示径向限制的二维等离子体滤波器，用于检测选定带宽上的辐射。该项目的目标是实现基于GaN/AlGaN纳米结构的异质结多通道FET探测器阵列，在0.5 - 5 THz频率范围内提供良好的探测响应度，并研究其在室温下的性能。利用电子束光刻和等离子体刻蚀技术在Si衬底上的GaN外延层上形成了悬浮的GaN纳米结构（芯）阵列。AlGaN壳将生长在GaN核上以形成核/壳异质结纳米结构。实现纳米结构场效应晶体管与尺寸限制的载体等离子体太赫兹检测是EAGER建议的目标。异质结的物理属性将被改变以调整器件性能。还将研究具有不同天线几何形状的辐射的耦合。探测器阵列FET的表征包括测量，以建立响应率和噪声等效功率（NEP）等品质因数。智力价值：该项目的智力价值集中在新型核/壳纳米结构多通道FET器件设计的大规模阵列架构所带来的挑战和机遇上。这个项目将推进我们对太赫兹辐射与纳米结构中径向受限电子气相互作用的理解。利用GaN/AlGaN界面处的高电子气密度的性质以及通过使用纳米级器件架构而改善的等离子体波速度和频率，可以在室温下实现太赫兹频率范围内的检测。该研究将通过使用缠绕门架构（用于更好的电压控制）来演示电子可调THz检测。这项研究将解决的基本问题，如果几何约束的载流子等离子体，使高性能可调谐太赫兹探测在室温下。本研究将探讨各种核/壳纳米结构器件参数和天线结构对探测器性能的影响。本研究的目的是建立一个新的范式为核心/壳纳米结构为基础的太赫兹探测器件。更广泛的影响：本项目的成功完成将推进我们的理解太赫兹与新的纳米结构核/壳器件架构，提高探测器的性能在室温下。该项目的结果也将对开发用于焦平面阵列（FPA）集成的高性能氮化物基异质结纳米结构FET阵列产生重大影响。这种FPA可以用于癌症检测的真实的THz成像以及国土安全和国防应用。一名研究生将在NIST最先进的纳米制造设施中获得实践经验。这项工作的结果将被纳入GMU电子轨道的研究生课程。高中生将在夏季从事该项目。

Overview:In recent years terahertz technology has gained significant interest, as the terahertz rays are non-ionizing and have appealing applications in security screening, homeland security, radio astronomy, manufacturing, communication and bio-sensing. The proposed research will demonstrate the viability of GaN/AlGaN core/shell nanostructure based multi-channel field-effect transistor (FET) arrays for sensing of Terahertz (THz) radiation in the range 0.5 to 5 THz using plasmonic excitations of the two-dimensional electron gas in such structures. By using novel design and fabrication strategies, high electron gas density with improved plasma wave velocities and frequencies are feasible, which will ensure the operation of these detectors at room temperature. The broad reaching goals of this basic research are two-fold: 1) to observe resonant detection with good quality factor with frequency tunability at room temperature and 2) to develop a design strategy for demonstrating radially-confined two-dimensional Plasmon filters for detecting radiation over a selected bandwidth. The objective of this project is to realize GaN/AlGaN nanostructure based heterojunction multi-channel FET detector arrays, to provide good detection responsivity in the frequency range of 0.5-5 THz, and study their performance at room temperature. Suspended GaN nanostructure (core) arrays will be formed by using electron beam lithography and plasma-etch techniques on epilayers of GaN on Si substrate. AlGaN shells will be grown on the GaN cores to form core/shell heterojunction nanostructures. Realization of nanostructure FETs with dimensionally confined carrier plasma for THz detection is the goal of this EAGER proposal. Physical attributes of the hetero-junction will be varied to tune the device performance. Coupling of the radiation with different antenna geometries will also be investigated. The characterization of detector array FETs includes measurements to establish figure of merits like responsivity and noise equivalent power (NEP).Intellectual Merit :The project's intellectual merit centers on the challenges and opportunities offered by the large-scale arrayed architecture of novel core/shell nanostructure multi-channel FET device design. This project will advance our understanding of the interactions of THz radiation with radially-confined electron gases in nanoscale structures. Detection in the THz frequency regime at room temperature can be realized by exploiting the property of high electron gas density at the GaN/AlGaN interface and the improved plasma wave velocities and frequencies by the use of nanoscale device architectures. The research will demonstrate electronically-tunable THz detection by the use of wrapped gate architectures (for better voltage control). This study would address the fundamental question if the geometrically confined carrier plasma enable high performance tunable THz detection at room temperatures. This study will investigate the effect of the various core/shell nanostructure device parameters and antenna structures on the detector performance. This research aims to establish a new paradigm for core/shell nanostructure based THz detection devices.Broader Impacts:Successful completion of this project will advance our understanding of the THz interaction with the novel nanostructure core/shell device architectures for improved detector performance at room temperature. Results of this project will also have a significant effect on the development of high-performance nitride-based heterojunction nanostructure FET arrays for integration in focal plane arrays (FPA). Such FPAs can be used in real time THz imaging for cancer detection, and homeland security and defense applications. A graduate student will get hands-on experience in a state of the art nanofabrication facility at NIST. Results of this work will be integrated into a graduate level course in the electronics track at GMU. High school students will work on the project during summer.