Surface Charge Transfer Kinetics in Atomically Thin Oxide Semiconductors

The electronic tunability of ultrathin oxide semiconductors approaching the 2D limit has been identified as a key advantage for realizing advanced electronic applications, yet the underlying mechanisms remain unclear. In this talk, I will reveal that charge transfer dynamics of surface oxygen is the dominant factor governing the electronic properties of ultrathin In₂O₃, particularly impacting the threshold voltage shifts in field-effect transistors. Through experimental analysis and kinetic modeling, we demonstrate that charge transfer, adsorption, and desorption of surface oxygen modulate the local charge density as undergoing electrostatic, optical and thermal stimuli. This work is broadly applicable to all oxide-based semiconductor devices, offering insights for designing advanced oxide devices. To further tailor electronic properties, I show that fluorine plasma doping could be a effective surface modification strategy. This mild-plasma treatment reduces excess electron density, addressing the challenge of balancing high mobility with effective switching in atomically thin In₂O₃. Using this method, we achieve a mobility exceeding 100 cm² V⁻¹ s⁻¹ while significantly improving switching characteristics in ultrathin oxide transistors. Our findings provide critical insights into the transport and reliability challenges of oxide semiconductors, offering a deeper understanding of their electronic properties and potential for advanced device applications.