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. 2021 Oct 27;14(21):6448.
doi: 10.3390/ma14216448.

Relaxor-Ferroelectric Films for Dielectric Tunable Applications: Effect of Film Thickness and Applied Electric Field

Minh D Nguyen  1   2 , Doan T Tran  2 , Ha T Dang  2   3 , Chi T Q Nguyen  2   3 , Guus Rijnders  1 , Hung N Vu  2
Affiliations

Relaxor-Ferroelectric Films for Dielectric Tunable Applications: Effect of Film Thickness and Applied Electric Field

Minh D Nguyen et al. Materials (Basel). .

Abstract

The dielectric properties, tunability and figure-of-merit (FOM) of relaxor Pb0.9La0.1(Zr0.52Ti0.48)O3 (PLZT) films have been investigated. Dielectric measurements indicated that the dielectric constant (at zero-bias field), tunability and FOM are enhanced as the film thickness increases, which are mainly attributed to the presence of an interfacial layer near the film-electrode interface. Experimental results illustrated that a slight reduction is observed in both dielectric constant and tunability (-2%) in a wide-frequency range (10 kHz-1 MHz); meanwhile, the FOM value decreases significantly (-17%) with increasing frequency, arising from the higher dielectric loss value. The 1000-nm PLZT film shows the largest tunability of 94.6% at a maximum electric-field of 1450 kV/cm, while the highest FOM factor is 37.6 at 1000 kV/cm, due to the combination of medium tunability (88.7%) and low dielectric loss (0.0236). All these excellent results indicated that the relaxor PLZT films are promising candidates for specific applications in microwave devices.

Keywords: dielectric properties; figure-of-merit; relaxor ferroelectrics; tunability.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
(a) XRD theta-2theta patterns and (b) corresponding cross-section SEM images of PLZT films.
Figure 2
Figure 2
Dielectric constant–electric field (ε-E) curves of (a) 250-nm, (b) 500-nm and (c) 1000-nm PLZT films, as a function of frequency. (d) Comparison of ε-E curves of PLZT films measured at 100 kHz. The measurements were performed at 800 kV/cm.
Figure 3
Figure 3
(a) Tunability curves which were calculated from the corresponding dielectric constant curves (Figure 2d), and (b) dielectric loss curves, of PLZT films as a function of film thickness measured at 800 kV/cm and 100 kHz.
Figure 4
Figure 4
Operating frequency dependent (a) dielectric constant at zero field (εr,0V) and at certain bias field (εEap), (b) dielectric loss at zero field (tan δ), (c) tunability (T) and (d) figure-of-merit (FOM), of 1000-nm PLZT films. The measurements were done at 800 kV/cm.
Figure 5
Figure 5
(a) Electric field dependent ε-E curves of 1000-nm PLZT films measure at 100 kHz. Zoom-in (b) near the peaks and (c) in the high-field regions of ε-E curves.
Figure 6
Figure 6
Applied electric-field dependent (a) dielectric constant at zero field (εr,0V) and at certain bias field (εEap,max), (b) dielectric loss at zero field (tan δ), (c) tunability (T) and (d) figure-of-merit (FOM), of 1000-nm PLZT films. The measurements were done at a frequency of 100 kHz.
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