Super-High-Frequency Bulk Acoustic Resonators Based on Aluminum Scandium Nitride for Wideband Applications
Despite the dominance of bulk acoustic wave (BAW) filters in the high-frequency market due to their superior performance and compatible integration process, the advent of the 5G era brings up new challenges to meet the ever-growing demands on high-frequency and large bandwidth. Al<sub>1-x</...
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| Format: | Article |
| Language: | English |
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MDPI AG
2023-10-01
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| Series: | Nanomaterials |
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| Online Access: | https://www.mdpi.com/2079-4991/13/20/2737 |
| _version_ | 1827720263765065728 |
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| author | Wentong Dou Congquan Zhou Ruidong Qin Yumeng Yang Huihui Guo Zhiqiang Mu Wenjie Yu |
| author_facet | Wentong Dou Congquan Zhou Ruidong Qin Yumeng Yang Huihui Guo Zhiqiang Mu Wenjie Yu |
| author_sort | Wentong Dou |
| collection | DOAJ |
| description | Despite the dominance of bulk acoustic wave (BAW) filters in the high-frequency market due to their superior performance and compatible integration process, the advent of the 5G era brings up new challenges to meet the ever-growing demands on high-frequency and large bandwidth. Al<sub>1-x</sub>Sc<sub>x</sub>N piezoelectric films with high Sc concentration are particularly desirable to achieve an increased electromechanical coupling (<i>K<sub>t</sub></i><sup>2</sup>) for BAW resonators and also a larger bandwidth for filters. In this paper, we designed and fabricated the Al<sub>1-x</sub>Sc<sub>x</sub>N-based BAW resonators with Sc concentrations as high as 30%. The symmetry of the resonance region, border frame structure and thickness ratio of the piezoelectric stack are thoroughly examined for lateral modes suppression and resonant performance optimization. Benefiting from the 30% Sc doping, the fabricated BAW resonators demonstrate a large effective electromechanical coupling (<i>K<sub>eff</sub></i><sup>2</sup>) of 17.8% at 4.75 GHz parallel resonant frequency. Moreover, the temperature coefficient of frequency (TCF) of the device is obtained as −22.9 ppm/°C, indicating reasonable temperature stability. Our results show that BAW resonators based on highly doped Al<sub>1-x</sub>Sc<sub>x</sub>N piezoelectric film have great potential for high-frequency and large bandwidth applications. |
| first_indexed | 2024-03-10T21:00:57Z |
| format | Article |
| id | doaj.art-b86437a84e644aa7a6eb6b10050a8c0b |
| institution | Directory Open Access Journal |
| issn | 2079-4991 |
| language | English |
| last_indexed | 2024-03-10T21:00:57Z |
| publishDate | 2023-10-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Nanomaterials |
| spelling | doaj.art-b86437a84e644aa7a6eb6b10050a8c0b2023-11-19T17:35:21ZengMDPI AGNanomaterials2079-49912023-10-011320273710.3390/nano13202737Super-High-Frequency Bulk Acoustic Resonators Based on Aluminum Scandium Nitride for Wideband ApplicationsWentong Dou0Congquan Zhou1Ruidong Qin2Yumeng Yang3Huihui Guo4Zhiqiang Mu5Wenjie Yu6School of Information Engineering, Southwest University of Science and Technology, Mianyang 621010, ChinaState Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, ChinaState Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, ChinaShanghai Engineering Research Center of Energy Efficient and Custom AI IC, School of Information Science and Technology, ShanghaiTech University, Shanghai 201210, ChinaSchool of Information Engineering, Southwest University of Science and Technology, Mianyang 621010, ChinaState Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, ChinaState Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, ChinaDespite the dominance of bulk acoustic wave (BAW) filters in the high-frequency market due to their superior performance and compatible integration process, the advent of the 5G era brings up new challenges to meet the ever-growing demands on high-frequency and large bandwidth. Al<sub>1-x</sub>Sc<sub>x</sub>N piezoelectric films with high Sc concentration are particularly desirable to achieve an increased electromechanical coupling (<i>K<sub>t</sub></i><sup>2</sup>) for BAW resonators and also a larger bandwidth for filters. In this paper, we designed and fabricated the Al<sub>1-x</sub>Sc<sub>x</sub>N-based BAW resonators with Sc concentrations as high as 30%. The symmetry of the resonance region, border frame structure and thickness ratio of the piezoelectric stack are thoroughly examined for lateral modes suppression and resonant performance optimization. Benefiting from the 30% Sc doping, the fabricated BAW resonators demonstrate a large effective electromechanical coupling (<i>K<sub>eff</sub></i><sup>2</sup>) of 17.8% at 4.75 GHz parallel resonant frequency. Moreover, the temperature coefficient of frequency (TCF) of the device is obtained as −22.9 ppm/°C, indicating reasonable temperature stability. Our results show that BAW resonators based on highly doped Al<sub>1-x</sub>Sc<sub>x</sub>N piezoelectric film have great potential for high-frequency and large bandwidth applications.https://www.mdpi.com/2079-4991/13/20/2737bulk acoustic wavefilm bulk acoustic resonatoraluminum scandium nitrideeffective electromechanical coupling coefficientspurious modes |
| spellingShingle | Wentong Dou Congquan Zhou Ruidong Qin Yumeng Yang Huihui Guo Zhiqiang Mu Wenjie Yu Super-High-Frequency Bulk Acoustic Resonators Based on Aluminum Scandium Nitride for Wideband Applications Nanomaterials bulk acoustic wave film bulk acoustic resonator aluminum scandium nitride effective electromechanical coupling coefficient spurious modes |
| title | Super-High-Frequency Bulk Acoustic Resonators Based on Aluminum Scandium Nitride for Wideband Applications |
| title_full | Super-High-Frequency Bulk Acoustic Resonators Based on Aluminum Scandium Nitride for Wideband Applications |
| title_fullStr | Super-High-Frequency Bulk Acoustic Resonators Based on Aluminum Scandium Nitride for Wideband Applications |
| title_full_unstemmed | Super-High-Frequency Bulk Acoustic Resonators Based on Aluminum Scandium Nitride for Wideband Applications |
| title_short | Super-High-Frequency Bulk Acoustic Resonators Based on Aluminum Scandium Nitride for Wideband Applications |
| title_sort | super high frequency bulk acoustic resonators based on aluminum scandium nitride for wideband applications |
| topic | bulk acoustic wave film bulk acoustic resonator aluminum scandium nitride effective electromechanical coupling coefficient spurious modes |
| url | https://www.mdpi.com/2079-4991/13/20/2737 |
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