Ferroelectric Control of Conduction in The Pb(Zr_0.2Ti_0.8)O₃/Bi₂O₂Se Heteroepitaxy

<b>The search for 2D semiconductors with excellent electronic performance and stability in the ambient environment is urgent. Bi₂O₂Se, an air-stable layered oxide, has emerged as a promising new semiconductor with excellent electronic properties. Studies demonstrate that its layered nature makes it ideal for fabricating electronic devices down to a few atomic layers. The Bi₂O₂Se-based top-gated field-effect transistor device shows excellent semiconductor device properties, including high carrier mobility (~28,900 cm2/Vs at 1.9 K and 450 cm2/Vs at room temperature) and superior current on/off ratio with the almost ideal subthreshold swing. In addition, the moderate bandgap (~0.8 eV) of Bi₂O₂Se makes its device suitable for room temperature operation while requiring only a relatively low operation voltage. These fascinating properties, chemical stability in the ambient environment, and easy accessibility make Bi₂O₂Se a promising semiconductor candidate for future ultra-small, high-performance, and low-power electronic devices. Moreover, as the Bi-O layer in Bi₂O₂Se is structurally compatible with many perovskite oxides with interesting physical phenomena, it is feasible to fabricate heteroepitaxy/superlattices between Bi₂O₂Se and perovskite oxides to pursue novel emergent physical phenomena in hybrid heterostructuresThethe study combines an epitaxial ferroelectric Pb(Zr_0.2Ti_0.8)O₃ (PZT) layer with the Bi₂O₂Se layer. The ferroelectric polarization of the PZT layer serves as a control parameter to modulate the semiconducting behaviors of the Bi₂O₂Se layer. The as-grown polarization leads to charge depletion and, consequently, low conduction. Switching the polarization direction results in charge accumulation and enhances the conduction at the Bi₂O₂Se layer. The origin of this modulation is attributed to a change in the electronic structure due to the ferroelectric polarization states, evidenced by X-ray photoelectron spectroscopy and cross-sectional scanning tunneling microscopy/spectroscopy. Control of the conduction at this new heterostructure delivers a pathway of non-volatile controlling on layered semiconductors for next-generation transistors.</b>