Heterogeneous integration of high endurance ferroelectric and piezoelectric epitaxial BaTiO$_3$ devices on Si

TL;DR

This paper presents a novel two-step method for integrating high-quality, high-endurance ferroelectric BaTiO$_3$ devices onto silicon, enabling advanced microelectronic applications with improved durability and performance.

Contribution

The authors develop a new two-step synthesis and transfer process for epitaxial BaTiO$_3$ on silicon, demonstrating high endurance and addressing film cracking issues.

Findings

High-quality BaTiO$_3$ capacitors on Si with Pr of 7 μC/cm²

Endurance of over 10^6 switching cycles

Successful transfer and growth of large-area templated layers

Abstract

Integrating epitaxial BaTiO$_3$ (BTO) with Si is essential for leveraging its ferroelectric, piezoelectric, and nonlinear optical properties in microelectronics. Recently, heterogeneous integration approaches that involve growth of BTO on ideal substrates followed by transfer to a desired substrate show promise of achieving excellent device-quality films. However, beyond simple demonstrations of the existence of ferroelectricity, robust devices with high endurance were not yet demonstrated on Si using the latter approach. Here, using a novel two-step approach to synthesize epitaxial BTO using pulsed laser deposition (PLD) on water soluble Sr3Al2O7 (SAO) (on SrTiO$_3$ (STO) substrates), we demonstrate successful integration of high-quality BTO capacitors on Si, with Pr of 7 uC/cm2, Ec 150 kV/cm, ferroelectric and electromechanical endurance of greater than $10^6$ cycles. We further address the challenge of cracking and disintegration of thicker films by first transferring a large area (5 mm x 5 mm) of the templated layer of BTO (~30 nm thick) on the desired substrate, followed by the growth of high-quality BTO on this substrate, as revealed by HRXRD and HRSTEM measurements. These templated Si substrates offer a versatile platform for integrating any epitaxial complex oxides with diverse functionalities onto any inorganic substrate.