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，在安全屏蔽、国土安全、射电天文、制造、通信和生物传感方面有着诱人的应用。这项拟议的研究将证明基于GaN/AlGaN核/壳纳米结构的多沟道场效应晶体管(FET)阵列的可行性，该阵列利用这种结构中的二维电子气的等离子体激发来传感0.5到5 THz范围内的太赫兹(THz)辐射。通过采用新的设计和制造策略，高电子气密度和提高等离子体波速度和频率是可行的，这将确保这些探测器在室温下工作。这项基础研究的广泛目标有两个：1)在室温下观察具有良好品质因数和频率可调的谐振检测；2)开发一种设计策略，用于演示用于检测选定带宽上的辐射的径向受限二维等离子体滤光器。本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0.5-5THz的频率范围内提供良好的探测响应，并研究它们在室温下的性能。利用电子束光刻和等离子体刻蚀技术，在硅基GaN外延层上形成悬浮的GaN纳米结构(芯)阵列。AlGaN壳层将生长在GaN核上，形成核/壳异质结纳米结构。利用尺寸受限的载流子等离子体实现纳米结构场效应管的太赫兹探测是这一迫切提议的目标。异质结的物理属性将变化以调整器件性能。还将研究不同天线几何形状的辐射之间的耦合。探测器阵列FET的表征包括建立响应度和噪声当量功率(NEP)等优值系数的测量。智力优势：该项目的智力优势集中在新型核/壳纳米结构多通道FET器件设计的大规模阵列架构带来的挑战和机遇上。这个项目将促进我们对太赫兹辐射与纳米结构中辐射受限电子气相互作用的理解。利用GaN/AlGaN界面的高电子气密度特性和利用纳米器件结构改进的等离子体波速度和频率，可以实现室温下太赫兹频段的探测。这项研究将通过使用包裹的栅极结构(以更好地控制电压)来演示电子可调太赫兹检测。这项研究将解决几何约束载流子等离子体是否能够在室温下实现高性能可调太赫兹探测的根本问题。本研究将考察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。本研究旨在建立一种基于核/壳纳米结构的太赫兹探测器件的新范式。广泛的影响：该项目的成功完成将促进我们对太赫兹与新型纳米结构核/壳器件体系结构相互作用的理解，以提高室温下的探测器性能。该项目的结果还将对高性能氮化物基异质结纳米结构FET阵列的开发产生重大影响，用于焦平面阵列(FPA)的集成。这种FPA可用于癌症检测、国土安全和国防应用的实时太赫兹成像。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电子轨道的研究生水平课程。高中生将在暑期参与这个项目。

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.