Low-temperature processing of piezoelectric thin films using flash lamp annealing
2Department of Physics and Materials Science, University of Luxembourg, Belvaux, Luxembourg
Integration of piezoelectrics on glass can bring new functionalities, such as advanced haptics and loudspeakers, which could be part of future flat panel displays, mobile phones, windows... An industrial standard lead zirconate titanate (PZT), with its high piezoelectricity and transparency, is an obvious candidate for this integration. But it has a major drawback – its crystallization temperature is above 650 °C, which is beyond the processable limit of the majority of commercial glasses.
Flash lamp annealing enables a non-localized thermal treatment through an absorption of light with broad spectrum inside the sample. Recently it was applied to oxide films on temperature-sensitive substrates. However, macroscopic ferroelectric and piezoelectric properties of flash lamp annealed PZT films have not yet been demonstrated [1].
In this contribution, we will show, for the first time, crystallization and macroscopic properties of PZT thin films (with morphotropic phase boundary composition) grown directly on alumina-borosilicate glass through flash lamp annealing (Figure 1). With a maximum temperature applied to the films of 350 °C, this low temperature process allows integration on majority of commercial glasses.
The films crystallize in perovskite phase and exhibit an in-plane permittivity of 273 with dielectric losses below 1% and a remanent polarisation larger than 3.5 µC·cm-2 for an applied field of 300 kV·cm-2.
Figure 1: a) X-ray diffraction pattern of a PZT thin film on glass crystallized by flash lamp annealing; Inset: Schematic of sample heating by flash lamp annealing; b) Polarization versus electrical field loop of same PZT thin film on glass crystallized by flash lamp annealing.
[1] Y. Yao et al., J. Eur. Ceram. Soc. 40, 5369-5375 (2020)
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