Role of Rare‐Earth Lanthanum Doping on Electrical Performance and Stability of Atomic Layer Deposition Processed Indium Oxide Thin‐Film Transistors

In this work, lanthanum‐doped indium oxide (InLaO) thin‐film transistors (TFTs) are fabricated by atomic layer deposition (ALD) with different La concentrations. Effects of La concentration on crystallinity, surface chemical information, surface morphology, along with the electrical properties of ALD‐grown InLaO TFTs, are systematically investigated. With increasing La content from 0 to 20.2 at. %, the field‐effect mobility (µ FE ) continuously decreases from 106.3 to 2.3 cm 2 (V·s) −1 . In contrast, the negative bias stability (NBS) is remarkably enhanced, and the threshold voltage (V TH ) shifts from −0.157 to −0.005 V under −2 V bias stress for 1000 s. This trend is attributed to the stronger La─O bonding energy compared to In─O. The stable La─O bonds effectively suppress the generation of oxygen vacancies (V O ) and associated defect states, which explains the superior stability. Concurrently, these bonds also restrain the formation of conduction pathways, leading to the observed mobility degradation. This work demonstrates that La doping is an effective strategy to precisely tune the stability‐mobility balance in oxide TFTs.