Integration of Imprint-Free and Low Coercivity Ferroelectric BaTiO₃ Thin Films on Silicon

Highly crystalline ferroelectric oxides integrated on Si hold great promise for energy-efficient memory and logic technologies. Exploiting epitaxial strain engineering in these materials is, however, severely hampered on Si, where the large structural mismatch often results in an inferior interfacial quality and causes degradation of the ferroelectric switching characteristics. In this work, we present the growth of single-crystalline BaTiO₃ thin films on Si, exhibiting imprint-free switching, low coercivity, high remanent polarization, and no fatigue for over 10¹⁰ switching cycles. We accomplish this via the insertion of a SrSn_1-xTi_xO₃ layer on SrTiO₃-buffered Si. This layer serves as a pseudosubstrate that alleviates the thermal strain that the Si substrate imposes on the BaTiO₃ layer, while simultaneously providing moderate compressive strain that stabilizes a pure out-of-plane polarization. Thus, our work paves the way toward the fabrication of Si-compatible, low-power-consuming ferroelectric devices.