Effects of Mn-doping on surface acoustic wave properties of ZnO films

• Published in: Physica status solidi. PSS-RRL. Rapid research letters 2012-11, Vol.6 (11), p.436-438
• Main Authors: Luo, J. T., Fan, P., Pan, F., Zeng, F., Zhang, D. P., Zheng, Z. H., Liang, G. X., Cai, X. M.
• Format: Article
• Language: English
• Subjects: doping; Electromagnetics; electromechanical properties; piezoelectric properties; surface acoustic waves; Surface chemistry; Thin films; ZnO
• ISSN: 1862-6254; 1862-6270
• DOI: 10.1002/pssr.201206381

Surface acoustic wave (SAW) filters based on Mn‐doped ZnO films have been fabricated and effects of Mn‐doping on SAW properties are investigated. It is found that the electromechanical coupling coefficient (K2) of Zn0.913Mn0.087O films is 0.73 ± 0.02%, which is 73.8% larger than that of undoped ZnO films (0.42 ± 0.02%). Zn0.913Mn0.087O film filters also exhibit a lower absolute value of insertion loss (|IL|) of 16.1 dB and larger bandwidth (BW) of 5.9 MHz compared with that of undoped ZnO film filter. However, Zn0.952Mn0.048O film filters exhibit a smaller K2 of 0.34 ± 0.02%, larger |IL| of 26.9 dB and smaller BW of 3.5 MHz. It is suggested that the SAW properties can be improved by appropriate Mn‐doping and Mn–ZnO/Si multilayer structure with large d33 is promising for wide‐band and low‐loss SAW applications. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) The piezoelectric coefficient d33 of ZnO:Mn films is a key factor determining the performance of ZnO:Mn/Si surface acoustic wave (SAW) devices, and the SAW properties can be improved by doping with an appropriate Mn concentration. The absolute value of the insertion loss is inversely proportional to d33, while the electromechanical coupling coefficient and bandwidth are both proportional to d33. A Mn–ZnO/Si multilayer structure with large d33 is promising for high frequency, wide‐band and low‐loss SAW applications.