Collaborative Research: Defect Immune, Topologically Protected Devices for Ultra-Low Power Electronics

材料中的缺陷，如缺陷或边缘粗糙度，往往严重限制电子设备的性能。这在纳米尺度上尤其成问题，因为即使是一个单一的原子缺陷也可能严重扰乱运输。因此，能够容忍这些缺陷的设备是未来技术的关键。通过新型2D和3D拓扑绝缘体(TIS)，提出了两种新的容错器件概念的基本属性和集成的研究，它们展示了只有使用这些独特材料才能实现的前所未有的低功率、室温性能和功能。这种对缺陷的容忍将使纳米电子学超越目前已知的限制，并将特别影响实现超低功率后硅电子学的国家重大挑战，并代表着国家技术实力领域半导体电子学的重大进步。一个具有互补专业知识的研究小组，包括初级调查人员和有经验的资深教授，将应对拟议工作的挑战。这项研究还将扩大科学和教育的参与，例如，通过NSF赞助的本科生研究体验(REU)项目以及与国家实验室和行业合作伙伴的合作，建立一个激励大学学习科学和工程的预科和本科生渠道。研究人员还将通过科学咖啡馆项目吸引公众参与，在那里，教师们在当地的酒吧和餐馆展示他们的研究。这个合作研究团队将阐明基于拓扑绝缘体(TI)的新型纳米电子器件概念的基本科学和技术含义，这种器件可以在低功率、远高于室温的情况下运行。未来将进行两项互补的研究工作，这两项工作都将有助于实现由铋基材料制成的新型超低功耗、拓扑保护的器件：1)不受材料和器件缺陷(如缺陷和线边缘粗糙度)影响的2D TI基场效应晶体管；2)基于3D TI的隧道器件，其利用自旋滤波来显示负阻，具有前所未有的峰谷比性能。分子束外延(Hinkle)生长钛的主要方向是2DBi2Se3和3DBi2Se3，它们有望在室温器件中得到应用。将使用原位技术(Wallace)研究表面和边缘状态检测以及化学/结构特性。理论研究包括密度泛函理论(DFT)、散射和迁移率计算(Vandenberghe)。先进的2端子和3端子器件将被制造出来(Banerjee)，这些器件特性将在与非门中进行评估。这项研究将为使用TIS的先进的低功耗、高性能逻辑、存储器甚至振荡神经形态应用提供材料和设备概念，TIS是一类对缺陷/杂质具有极强健壮性的设备。通过与NIST的合作，还将建立一个TI和2D材料属性和基准数据库。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Imperfections in materials, such as defects or edge roughness, often severely limit electronic device performance. This is especially problematic at the nanoscale where even a single atomic defect can drastically disrupt transport. Devices that are tolerant to these imperfections are thus the key to future technologies. The investigation of the fundamental properties and integration of two new defect-tolerant device concepts is proposed, enabled by novel 2D and 3D topological insulators (TIs), that exhibit unprecedented low-power, room temperature performance and functionalities only achievable using these unique materials. This tolerance to defects will enable nanoelectronics beyond the currently known limits and will specifically impact the national grand challenge of enabling ultra-low-power, post-silicon electronics and represent significant progress in an area of national technological strength, semiconductor electronics. A team of researchers with complementary expertise, including junior investigators complemented by accomplished senior professors, will address the challenges of the proposed work. This research will also broaden scientific and educational participation by creating a pipeline of pre-college and undergraduate students motivated to study science and engineering at universities through, for example, NSF-sponsored Research Experiences for Undergraduates (REU) programs and collaborations with national laboratories and industry partners. The researchers will also engage the public through science cafe programs where faculty members present their research in local pubs and restaurants.This collaborative research team will elucidate the fundamental science and technological implications of new topological insulator (TI)-based nanoelectronic device concepts that can operate at low-power, well above room temperature. Two complementary research threads will be pursued, both of which will enable a new, ultra-low-power, topologically protected device made of bismuth-based materials: 1) a 2D TI-based field-effect transistor that is immune to materials and device imperfections such as defects and line-edge roughness, and 2) a 3D TI-based tunneling device utilizing spin-filtering to exhibit negative differential resistance with unprecedented peak-to-valley ratio performance. TI growth by molecular beam epitaxy (Hinkle) will focus on 2D Bi and 3D Bi2Se3, which have predicted room-temperature device applications. Surface and edge state detection and chemical/structural properties will be investigated using in-situ techniques (Wallace). Theoretical studies including density functional theory (DFT), scattering, and mobility calculations (Vandenberghe) will be employed. Advanced 2- and 3-terminal devices will be fabricated (Banerjee) and these device characteristics will be evaluated in NAND gates. This research will provide materials and device concepts for advanced low-power, high-performance logic, memory, and even oscillatory neuromorphic applications using TIs, a class of devices which are extremely robust against defects/impurities. A TI and 2D materials property and benchmarking database through collaboration with NIST will also be established.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.