Spalled Barium Titanate Single Crystal Thin Films for Functional Device Applications

Area of Science:

• Materials Science
• Crystallography
• Optoelectronics

Background:

• Conventional thin film fabrication methods struggle to produce large-area, high-quality single-crystal microstructures.
• This limitation hinders the performance of functional devices reliant on precise crystalline orientation.

Purpose of the Study:

• To introduce a scalable fabrication technique for single-crystal barium titanate (BTO) thin films.
• To demonstrate the potential of spalling for producing high-performance thin films for optoelectronic applications.

Main Methods:

• Utilizing stress-induced exfoliation (spalling) from bulk single-crystal substrates.
• Controlling thin film thickness from 100 nm to 15 μm and lateral dimensions up to several millimeters.
• Performing electro-optic characterization to determine Pockels coefficients.

Main Results:

• Successfully fabricated single-crystal BTO thin films with controllable thickness and large lateral dimensions.
• Measured Pockels coefficients of r33 = 55 pm/V (multidomain) and 160 pm/V (single-domain).
• Projected r42 coefficient up to 1980 pm/V under unclamped conditions.

Conclusions:

• Spalled BTO single-crystal thin films retain bulk electro-optic properties.
• The performance of these spalled films surpasses that of commercial thin film lithium niobate.
• These films are highly suitable for integration into advanced photonic and optoelectronic devices.