Interfacial Oxygen Coordination Controlled by Mo, Cu, and Cr Electrodes in ALD-Grown IGZO Thin-Film Transistors

The performance of thin-film transistors (TFTs) is strongly influenced not only by the semiconductor layer but also by the nature of the electrical contact between source and drain electrodes and the semiconductor, which critically governs carrier injection and transport. Here, the effects of Mo, Cu, and Cr source/drain electrodes on the interfacial electronic structure and device performance of the ALD-grown IGZO TFTs were systematically investigated. The results show that Mo and Cr induce partial In–O bond dissociation at the IGZO surface, forming In-rich coordination and increasing oxygen-vacancy-related states, whereas Cu preserves intrinsic oxygen coordination. These interfacial variations directly control carrier injection and bias stress behavior. Mo-contacted devices exhibit more conductive interfaces, yielding higher mobility and improved positive-bias stability, while Cu-contacted devices show reduced negative-bias shifts due to lower vacancy concentrations. Cr-contacted devices form an interfacial Cr2O3 layer, increasing contact resistance and suppressing mobility. These results clarify the role of electrode-induced interfacial chemistry in oxide TFTs and provide practical guidance for optimizing mobility and stability in display and oxide circuit applications.