Lead-free (Bi0.5Na0.5)TiO3-based thin films by the pulsed laser deposition process

Area of Science:

• Materials Science
• Solid State Physics
• Thin Film Technology

Background:

• Ferroelectric thin films are crucial for advanced electronic devices.
• Bismuth sodium titanate-based materials offer promising piezoelectric and ferroelectric properties.
• Controlling deposition parameters is key to optimizing thin film performance.

Purpose of the Study:

• To investigate the impact of pulsed laser deposition parameters on the properties of 0.88(Bi(0.5)Na(0.5))TiO(3)-0.08(Bi(0.5)K(0.5))TiO(3)-0.04BaTiO(3) thin films.
• To identify optimal deposition conditions for enhanced microstructure, crystallinity, and ferroelectric characteristics.
• To understand the relationship between oxygen pressure and film quality.

Main Methods:

• Pulsed laser deposition (PLD) of ferroelectric thin films.
• Systematic variation of deposition parameters: temperature, repetition rate, oxygen pressure, and laser energy.
• Characterization of film microstructure, crystallinity, dielectric properties, and ferroelectric behavior.

Main Results:

• Optimal ferroelectric properties were achieved at 800°C, 10 Hz, 400 mtorr oxygen pressure, and 1.2 Jcm(-2) laser energy.
• These optimal conditions resulted in a remanent polarization of ~30 μCcm(-2), a dielectric constant of 645 at 1 kHz, and a coercive field of 85 kVcm(-1).
• Increasing oxygen pressure from 200 to 400 mtorr improved crystallinity, microstructure, dielectric constant, and polarization, while suppressing leakage current and dielectric loss.

Conclusions:

• Deposition parameters critically influence the ferroelectric properties of BNT-BKT-BT thin films.
• Optimized PLD conditions, particularly oxygen pressure, are essential for high-performance ferroelectric thin films.
• Reduced oxygen vacancies and improved surface morphology at higher oxygen pressures contribute to enhanced film quality.