Multi‐Channel, Amorphous Oxide Thin‐Film Transistor Exhibiting High Mobility of 67 cm² V⁻¹ s⁻¹ and Excellent Stability

Abstract Multi‐channel amorphous oxide thin‐film transistors (TFTs) with dual gate (DG), coplanar structure are studied. The multi‐channel consists of a top amorphous indium gallium zinc tin oxide (a‐IGZTO) and a very thin amorphous indium zinc oxide (a‐IZO) bottom layer. The fabricated TFTs exhibit high field‐effect mobility (µ FE ) ≈67.1 cm 2 V −1 s −1 , and excellent stability under positive bias temperature stress (PBTS). The band diagram of the multi‐channel TFT is presented based on UV photoelectron spectroscopy, X‐ray photoelectron spectroscopy, and UV–vis spectroscopy measurements. The PBTS robustness is interpreted as the formation of 2D electron gas (2DEG) at the a‐IGZTO/a‐IZO hetero‐interface which extends to the bulk a‐IZO layer. From thermalization energy (E Th ) analysis with the energy barrier to defect formation under PBTS, the multi‐channel TFT exhibits the largest E Th of 0.84 eV, which indicates that more stress energy is needed for threshold voltage shift during PBTS in the TFTs as compared to single‐channel TFTs.