Stoichiometry-engineered SiO_x/KTaO₃ interfaces with photoelectric coupling modulation of the transport

Two-dimensional electron gases at oxide interfaces offer a promising platform for future electronic devices. Here, we demonstrate photoelectric modulation of transport properties at the SiO_x/KTaO₃ interface. High-quality SiO_x films were deposited on KTaO₃ substrates by pulsed laser deposition under controlled atmospheres. XPS analysis reveals that oxygen pressure critically determines the interfacial chemical state, with oxygen vacancies modulating carrier density. Transport measurements show metallic conductivity with carrier densities of ∼10¹³ cm^-2. Remarkably, introducing water vapor during growth significantly enhances mobility while reducing carrier density, attributed to hydroxyl-induced passivation and screening of remote Coulomb scattering. Magnetotransport studies reveal a weak antilocalization to weak localization transition accompanied by Rashba spin-orbit coupling. Furthermore, combined ultraviolet illumination and gate biasing enables reversible modulation of Rashba splitting, reaching a maximum of ∼27.18 meV. This photoelectric approach provides non-volatile control of oxide-based 2DEG spintronic properties for multifunctional quantum devices.