Collaborative Research: Characterization of Traps in GaInAs/GaAsSb Multiple Quantum Well Structures

技术。该合作项目涉及InGaAs/GaAsSb多量子阱（MQW）的材料科学生长/加工研究，以及针对中红外波长探测器应用的相关研究。带对准的性质允许通过改变层厚度、应变和成分来调整能隙。重点放在更好地理解GaInAs/GaAsSb mqw中的陷阱形成以及它们的形成与原型器件性能的相关性。该方法涉及使用InP来提供优势：这些优势包括使用压缩和拉伸应变材料进行柔性设备设计选项；成熟的晶圆代工能力，可加工基于inp的结构；利用过去十年中以创新产品为基础的外产值增长的进步的能力；以及利用InP电子驱动的未来进步的能力。目前，器件性能似乎受到吸收区中隙陷阱的限制；因此，这项工作的重点是提供对这些陷阱的更完整的理解，并将它们与设备性能相关联。虽然从器件的角度来看，这项工作中使用的MIR光电二极管测试结构具有其优点，但对GaInAs， GaAsSb和GaInAs/GaAsSb mqw中的陷阱态的基本了解将提高我们对这些材料的基本理解。反过来，这将有助于更好地理解基于sb的MQW结构的性质。此外，这些mqw还影响其他重要器件，如异质结双极晶体管和中红外半导体激光器。非技术。本项目涉及电子/光子材料科学中具有技术相关性的主题领域的基础研究问题。这些材料的拟议研究的社会效益可能是广泛的，因为所研究的材料和原型设备支持民用和军事应用，包括污染检测、医疗诊断、夜视和导弹跟踪。目前，最好的探测器是基于HgCdTe的带到带跃迁或使用III-V化合物半导体的量子阱红外探测器（qwip）。这两种技术都不适合在室温或室温附近操作。InGaAs/GaAsSb MQW探测器的一个重要优势是在相对较高的温度（200-300K）下具有高探测性的潜力。通过参与最先进的研究，研究生和本科生都将获得宝贵的技能，并更好地理解材料生长，表征，器件设计和器件制造之间的联系。为了展示中红外光电二极管对应用的影响，所开发的光电二极管将用于痕量气体监测演示平台。该平台将用于外展项目(工程开放日，一个名为工程入门（ITE）的暑期项目；以及ENGR 162 （UVA）和EG EG10111/10112 （Notre Dame）要求第一年的工程课程)，旨在说明电气工程的社会效益。这些外展活动的目标是(i)教育公众有关工程的知识，（ii）招募大学预科学生以工程为职业，（iii）激励一年级工程专业的学生在一年后继续学习本专业。

Technical. This collaborative project addresses materials science growth/processing research of InGaAs/GaAsSb multiple quantum wells (MQW) with related investigations aimed toward mid-IR wavelength detector applications. The nature of the band alignment allows tuning of the en-ergy gap by varying layer thickness, strain, and composition. Emphasis is placed on gaining greater understanding of the trap formation in GaInAs/GaAsSb MQWs and correlation of their formation with prototype device performance. The approach involves the use of InP to provide advantages: these include the use of compressive and tensile strained materials for flexible device design options; mature wafer foundry capabilities for processing InP-based structures; the ability to leverage advances in InP-based epi-growth over the past decade; and the ability to leverage fu-ture advances driven by InP electronics. Currently, device performance apppears limited by mid-gap traps in the absorption region; hence this work is focused on providing a more complete un-derstanding of these traps and correlating them with device performance. While the MIR photo-diode test structure used in this work has its merit from device perspectives, the basic under-standing of trap states in GaInAs, GaAsSb, and GaInAs/GaAsSb MQWs will improve our fun-damental understanding of these materials. In turn, this will help to better understand the nature of the Sb-based MQW structure. Additionally, these MQWs also impact other important devices such as heterojunction bipolar transistors and mid-IR semiconductor lasers. Non-Technical. The project addresses fundamental research issues in a topical area of elec-tronic/photonic materials science having technological relevance. Societal benefits of the pro-posed research of these materials are potentially broad since the materials and prototype devices being studied support civilian and military applications including pollution detection, medical di-agnostics, night vision, and missile tracking. At present, the best detectors are based on band-to-band transitions in HgCdTe or quantum-well infrared photodetectors (QWIPs) using III-V com-pound semiconductors. Neither technology is well-suited for operation at or near room-temperature. An important advantage of InGaAs/GaAsSb MQW detectors is the potential for high detectivity at relatively high temperatures (200-300K). Through their participation in state-of-the-art research both graduate and undergraduate students will gain invaluable skills and better understand the connection between materials growth, characterization, device design, and device fabrication. To show the impact of mid-IR photodiodes on applications, the photodiodes devel-oped will be used in a trace-gas monitoring demonstration platform. This platform will be used in outreach programs (Engineering Open House; a summer program called Introduction to Engi-neering (ITE); and ENGR 162 (UVA) and EG EG10111/10112 (Notre Dame) required first year engineering courses) designed to illustrate the societal benefits of Electrical Engineering. The goals of these outreach activities are to (i) educate the public about engineering, (ii) recruit pre-college students to pursue engineering as a career, and (iii) motivate first-year engineering students to remain in the major after their first year.