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Spray Pyrolysis Synthesized Self-biased Hexagonal Ferrite Thin Film on GaN, AlN, Si Substrates for Millimeter-wave Devices

用于毫米波器件的 GaN、AlN、Si 衬底上喷雾热解合成自偏置六方铁氧体薄膜

基本信息

批准号：
1808147
负责人：
Mohammed Afsar
金额：
$ 40万
依托单位：
Tufts University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2018
资助国家：
美国
起止时间：
2018-08-01 至 2021-07-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1808147&HistoricalAwards=false
关键词：
Spray Pyrolysis Synthesized Self biased

项目摘要

With the advent of advanced wireless communications the spectrum at lower frequencies are congested. To overcome this congestion an alternative approach is to develop compact and high efficient communication system using passive devices operating in millimeter-wave frequency band. The materials used at these frequencies are Ba- and Sr hexaferrites. The anisotropy of these ferrites exhibit strong ferromagnetic resonance up to 60 GHz (5 mm in wavelength). The oxygen molecule in the atmosphere exhibit a strong resonance absorption of electromagnetic waves at 60 GHz. Thus makes it a very attractive frequency band for shorter distance communication system. In current proposal, the use of self-biased hexagonal ferrite devices is suggested in millimeter wave frequencies. This led to shift from silicon, narrowband gap substrate technology to GaN, wideband gap substrate technology for efficient performance of communication system. The Ba- and Sr- ferrite nano size powders are now readily available from a number of manufacturers. Recently it has been found that nano-sized hexagonal ferrite powders can be mixed with commercially available photoresist and then sprayed as a layer on to the GaN substrate. It is proposed to use one ultrasonic generator with two ultrasonic spray nozzles with compressed air shaper for spraying. The next step turns out to be curing of the film in an oven up to 600 degrees centigrade for narrowing of the ferromagnetic resonance peak. It also leads to doubling of the resonance intensity. The comprehensive characterization study of deposited nano-ferrite film has been performed by employing a custom made quasi-optical millimeter wave spectrometer, scanning electron microscope, X-ray diffraction analysis and vibrating sample magnetometer.For a communication system, one would need a high efficient power amplifier, a low noise amplifier and a nano-ferrite circulator. However, the process to manufacture high quality nano-ferrite material with good grain size offer significant challenges. One of the problem is how to deposit self-bias hexagonal ferrite thin film with both good quality and acceptable cost has not been solved yet. Currently available wafers for MMIC design are about 100 mm in diameter with a thickness of about 100m. Typical thicknesses are 98 m of SiC and 2 m of GaN. The development of high purity GaN thick film film on SiC turns out to be big challenge in the near future. A thin film of highly pure wide bandgap semiconductor such as Aluminum Nitride can also be deposited on SiC. It is a new technology and it will be explored during the course of the proposed research period. Originally this work was explored on IBM silicon CMOS substrates. The lower temperature operation restricted the deposition of nano ferrite Ba- ferrite film to porosity and uneven flatness. The work with silicon CMOS substrate will also be continued. The collaborative partnership with QORVO has led to the use of GaN on SiC wafers routinely. The ultimate goal is to have Ba-ferrite circulator, power amplifier and low noise amplifier build on a single GaN on SiC wafer for operation at 60 GHz.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.

随着先进无线通信的出现，较低频率的频谱变得拥挤。为了克服这种拥塞，另一种方法是使用工作在毫米波频段的无源器件来开发紧凑高效的通信系统。在这些频率下使用的材料是Ba和Sr六角铁氧体。这些铁氧体的各向异性表现出强的铁磁共振高达60 GHz（5毫米波长）。大气中的氧分子对60 GHz的电磁波有很强的共振吸收。因此，它是一个非常有吸引力的频段，用于短距离通信系统。在当前的提议中，建议在毫米波频率中使用自偏置六角铁氧体器件。这导致了从硅、窄带间隙衬底技术向GaN、宽带间隙衬底技术的转变，以实现通信系统的高效性能。Ba-和Sr-铁氧体纳米尺寸粉末现在可容易地从许多制造商获得。最近已经发现，纳米尺寸的六方晶系铁氧体粉末可以与市售的光致抗蚀剂混合，然后作为层喷涂到GaN衬底上。提出采用一台超声波发生器配两个超声波喷嘴，并配以压缩空气整形器进行喷涂。下一步是在高达600摄氏度的烘箱中固化薄膜，以缩小铁磁共振峰。它还导致共振强度加倍。利用自制的准光学毫米波谱仪、扫描电镜、X射线衍射分析仪和振动样品磁强计对沉积的纳米铁氧体薄膜进行了综合表征研究。通信系统需要高效率的功率放大器、低噪声放大器和纳米铁氧体环行器。然而，制造具有良好晶粒尺寸的高质量纳米铁氧体材料的工艺提出了重大挑战。其中一个问题是如何存款自偏置六角铁氧体薄膜的质量和可接受的成本尚未解决。目前可用于MMIC设计的晶片直径约为100 mm，厚度约为100 m。典型的厚度是98 μ m的SiC和2 μ m的GaN。在SiC上开发高纯度GaN厚膜是近期的一大挑战。还可以在SiC上沉积高纯宽带隙半导体薄膜，例如氮化铝。这是一项新技术，将在拟议研究期间进行探索。最初这项工作是在IBM硅CMOS衬底上进行的。低温操作限制了纳米铁氧体钡铁氧体薄膜的沉积，导致薄膜的孔隙率和平整度不均匀.硅CMOS衬底的工作也将继续进行。与QORVO的合作伙伴关系使GaN在SiC晶片上的使用成为常规。最终目标是在单个GaN on SiC晶片上构建Ba铁氧体环行器、功率放大器和低噪声放大器，以在60 GHz下工作。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。