Solution-Processed Pb(Zr,Ti)O3 Thin Films with Strong Remnant Pockels Coefficient

This article investigates the electro-optic (EO) properties of solution-processed Pb(Zr,Ti)O₃ (PZT) thin films, focusing on their potential for integration into silicon photonics. While Pb(Zr,Ti)O₃ is widely recognized for its electrical properties, its EO properties remain underexplored, limiting its use in electro-optic applications. The study highlights the fabrication of highly textured, fiber-oriented PZT films using a La₂O₂CO₃ template and chemical solution deposition (CSD) process, which is essential for ensuring compatibility with various photonic platforms.

Key findings from the study include:

1. Film Fabrication and Properties:

• The PZT films exhibit a strong rhombohedral crystal phase (R3m) with a fiber texture. The films have a low surface roughness (RMS = 0.73 nm) and a predominant (h00) out-of-plane orientation, which is beneficial for electro-optic applications.

• The films are stabilized using a complexation process with Hacac (acetylacetone) to enhance the stability of the precursor solution.

2. Electro-Optic (EO) Characterization:

• The films demonstrate a maximum Pockels coefficient (reff) of 68.98 pm/V and a remnant reff of 65.95 pm/V, showing strong and stable EO response, which is crucial for phase modulation applications.

• The EO response is stable over time, with only minor transient phenomena observed in the first few hours after poling.

3. Device Integration:

• The PZT films were integrated into a silicon nitride (SiN) O-band ring resonator. The resulting device exhibits a VπL product of 2.019 V·cm and a Pockels coefficient of 94.50 pm/V.

• The ring resonator shows a linear wavelength shift in response to an applied voltage, with a tuning efficiency of 17.25 pm/V.

4. Material Performance:

• The PZT thin films' performance compares favorably with state-of-the-art materials for electro-optic modulators, offering a high degree of polarization stability and low loss, making them suitable for use in high-speed, low-power photonic devices.

In conclusion, the solution-based approach to fabricating Pb(Zr,Ti)O₃ thin films, using a La₂O₂CO₃ template, offers a promising pathway for integrating this material into silicon photonics, particularly for applications in electro-optic modulators. The strong EO properties, high stability, and compatibility with photonic platforms make these films highly attractive for next-generation data communication systems.