Heterogeneous Transfer of Thin Film BaTiO$_3$ onto Silicon for Device Fabrication

TL;DR

This paper presents a scalable method for synthesizing high-quality BaTiO$_3$ thin films via hybrid metal-organic MBE and transferring them onto silicon, enabling integration for electro-optic device applications.

Contribution

It introduces a hybrid metal-organic MBE process for high-quality BaTiO$_3$ film growth and a scalable transfer technique onto silicon for device fabrication.

Findings

High-quality BaTiO$_3$ films synthesized at >100nm/hr.

Successful transfer of crack-free, atomically flat films onto silicon.

Demonstration of sub-micron patterning on transferred films.

Abstract

Thin film BaTiO$_3$ has one of the highest known Pockels coefficients (>1200 pm/V), making it an attractive material for use in electro-optic devices. It is advantageous to integrate BaTiO$_3$ on silicon to enable complementary metal-oxide-semiconductor (CMOS) compatible processing. However, synthesis of high-quality BaTiO$_3$ directly on silicon remains a challenge. Here, we synthesize BaTiO$_3$ using hybrid metal-organic molecular beam epitaxy (hMBE) and demonstrate its transfer onto silicon using thermocompression bonding and chemical lift-off. Hybrid metal-organic MBE enables self-regulated synthesis of highly stoichiometric thin films at high growth rates (>100nm/hr). Our transfer method results in millimeter-scale areas of atomically flat, crack-free BaTiO$_3$ making it a potentially scalable method. Finally, we demonstrate the applicability of our process to device fabrication through characterization of lithographically-patterned and etch-transferred sub-micron features.