Oxygen-pressure driven balancing of interface and bulk scattering in amorphous oxide semiconductor thin-film transistors

Oxygen vacancies ( V O ) critically influence the electronic properties and stability of amorphous oxide semiconductor (AOS) thin-film transistors (TFTs). Here, we investigate the impact of oxygen partial pressure during film deposition on charge transport mechanisms in 10-nm-thick silicon-doped indium oxide (ISO) TFTs. By adjusting the Ar:O 2 ratio (11:1, 8:4, and 6:6), we observe a shift from interface-limited to bulk-scattering-dominated transport. Higher O 2 pressure leads to increased subthreshold swing (SS), positive threshold voltage ( V th ) shifts, and larger current fluctuations, suggesting greater charge trapping and mobility degradation. Low-frequency noise (LFN) analysis further reveals a shift in the dominant noise mechanism: interface charge trapping dominates at low O 2 pressure, while bulk carrier scattering prevails at high O 2 pressure. The extracted trap density ( N it ) increases by nearly two orders of magnitude, confirming the role of fully oxidized indium atoms in the conducting channel as charge-scattering centers. These findings establish oxygen pressure as a key parameter for balancing interface and bulk effects in AOS TFTs and provide a pathway for optimizing device performance and stability in next-generation oxide electronics. Oxygen Pressure Control steers charge transport from interface charge trapping to bulk scattering in silicon-doped In 2 O 3 thin-film transistors. Low-frequency noise analysis reveals that, with increasing O 2 partial pressure, fully oxidized indium atoms become active scattering centers. This study demonstrates an oxygen-engineering strategy to optimize device performance and stability.