CAREER:Doped Aluminum Nitride Ferroelectric Microelectromechanical Systems

职业：掺杂氮化铝铁电微机电系统

• 批准号: 1944248
• 负责人: Roy Olsson
• 金额: $ 50万
• 依托单位: University of Pennsylvania
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-02-01 至 2025-01-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1944248&HistoricalAwards=false
• 关键词: CAREER; Doped; Aluminum; Nitride; Ferroelectric

Proposal Title:CAREER: Doped Aluminum Nitride Ferroelectric Microelectromechanical SystemsNontechnical AbstractIn cellular phones, piezoelectric materials convert radio frequency signals into mechanical vibrations that form the miniature, highly selective, front-end filters critical to efficient utilization of the radio-frequency (RF) spectrum. While acoustic filter technologies are well developed in the existing cellular bands, miniature filtering technologies for mitigating interference are lacking in the Millimeter Wave bands that have been allocated for broadband fifth-generation (5G) cellular network technology. The proposed research will study new methods for scaling the frequency of acoustic front-end filtering technologies to the Millimeter Wave bands without the degradation in performance that plaques existing frequency scaling approaches. Success of the proposed research will enable reliable fifth-generation wireless networks that are more robust to interference. The applications will have major societal impacts.Technical AbstractThere are two grand challenges to overcome in acoustic filter technologies as they are scaled to meet the needs of wireless communication systems, such as fifth-generation (5G) mobile networks. First, as the frequency of acoustic resonators and filters are scaled beyond 6 giga Hertz (GHz), the dimensions rapidly shrink, significantly degrading the performance due to a litany of parasitic effects. These including degradation of the resonator quality factor arising from scattering at the resonator surfaces and from resistive losses in the thinned metal electrodes, and degradation of the resonator electromechanical coupling as the ratio of the device capacitance falls in comparison to the capacitance associated with on-chip routing to the tiny acoustic devices. Second, the fixed frequency operation of existing acoustic resonators limits the number of bands that can be added before the losses, area, and cost introduced by the routing and switches becomes unworkable. This research seeks to study and exploit the recently discovered ferroelectricity in aluminum scandium nitride (AlScN) thin films to address these fundamental challenges. The proposed research will develop material deposition techniques allowing for the systematic tailoring of the ferroelectric properties through the thickness of an aluminum scandium nitride film stack via variations in scandium doping. These techniques will be utilized to form film stacks where the coercive fields have been engineered to vary through the device thickness, allowing for the selective inversion of the ferroelectric polarization of specific regions in the aluminum scandium nitride films at controllable depths. Periodically poled layers through the film thickness will be realized to selectively excite high order overtone acoustic resonances that enable dramatic frequency scaling without the steep reductions in resonator dimensions that degraded both the quality factor and electromechanical coupling of prior frequency scaling attempts. The selective poling techniques will be extended to demonstrate acoustic resonators that can be dynamically reconfigured over many octaves in frequency. Finally, fundamental questions pertaining to the aluminum scandium nitride film properties that ultimately define the performance limits of the proposed radio-frequency (RF) devices will be explored.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.

提案标题：职业：掺杂氮化铝铁电微机电系统非技术摘要在手机中，压电材料将射频信号转换为机械振动，形成微型、高选择性的前端滤波器，这对于有效利用射频 (RF) 频谱至关重要。虽然声学滤波器技术在现有蜂窝频段中得到了很好的发展，但在已分配给宽带第五代 (5G) 蜂窝网络技术的毫米波频段中却缺乏用于减轻干扰的微型滤波技术。拟议的研究将研究将声学前端滤波技术的频率缩放到毫米波频段的新方法，而不会导致现有频率缩放方法的性能下降。拟议研究的成功将使可靠、抗干扰能力更强的第五代无线网络成为可能。这些应用将产生重大社会影响。技术摘要声学滤波器技术在扩展以满足第五代 (5G) 移动网络等无线通信系统的需求时需要克服两大挑战。首先，随着声学谐振器和滤波器的频率超过 6 GHz，尺寸迅速缩小，由于一系列寄生效应，性能显着下降。其中包括由于谐振器表面的散射和变薄的金属电极中的电阻损耗而引起的谐振器品质因数的下降，以及由于器件电容与与微型声学器件的片上布线相关的电容相比的比率下降而导致谐振器机电耦合的下降。其次，现有声学谐振器的固定频率操作限制了在路由和交换机引入的损耗、面积和成本变得不可行之前可以添加的频带数量。本研究旨在研究和利用最近发现的氮化铝钪 (AlScN) 薄膜中的铁电性来解决这些基本挑战。拟议的研究将开发材料沉积技术，通过钪掺杂的变化，通过氮化铝钪薄膜叠层的厚度来系统地调整铁电特性。这些技术将用于形成薄膜叠层，其中矫顽场被设计为随器件厚度变化，从而允许在可控深度选择性反转氮化铝钪薄膜中特定区域的铁电极化。将实现穿过薄膜厚度的周期性极化层，以选择性地激发高阶泛音声谐振，从而实现显着的频率缩放，而不会急剧减小谐振器尺寸，从而降低先前频率缩放尝试的品质因数和机电耦合。选择性极化技术将得到扩展，以演示可以在多个倍频程上动态重新配置频率的声谐振器。最后，将探讨与氮化铝钪薄膜特性有关的基本问题，这些问题最终定义了拟议射频 (RF) 设备的性能限制。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Controlling Residual Stress and Suppression of Anomalous Grains in Aluminum Scandium Nitride Films Grown Directly on Silicon

• DOI: 10.1109/jmems.2022.3167430
• 发表时间: 2022-05-06
• 期刊: JOURNAL OF MICROELECTROMECHANICAL SYSTEMS
• 影响因子: 2.7
• 作者: Beaucejour, Rossiny;Roebisch, Volker;Olsson, Roy H., III
• 通讯作者: Olsson, Roy H., III

Sub-quarter micrometer periodically poled Al0.68Sc0.32N for ultra-wideband photonics and acoustic devices

• DOI: 10.1063/5.0161423
• 发表时间: 2023-09-21
• 期刊: JOURNAL OF APPLIED PHYSICS
• 影响因子: 3.2
• 作者: Tang，Zichen;Esteves，Giovanni;Olsson，Roy H.
• 通讯作者: Olsson，Roy H.

Strongly enhanced second-order optical nonlinearity in CMOS-compatible Al 1−x Sc x N thin films

CMOS 兼容的 Al 1–x Sc x N 薄膜中二阶光学非线性得到显着增强

• DOI: 10.1063/5.0061787
• 发表时间: 2021
• 期刊: APL Materials
• 影响因子: 6.1
• 作者: Yoshioka, Valerie;Lu, Jian;Tang, Zichen;Jin, Jicheng;Olsson, Roy H.;Zhen, Bo
• 通讯作者: Zhen, Bo