ALD Al2O3-Engineered Schottky Barrier Interface for Amorphous Indium–Zinc Oxide

The interaction between metal and oxide semiconductors (OSs) is critical for advancing OS applications in large-area, flexible, and heterogeneously integrated electronics. Both ohmic and Schottky contacts are essential in these devices. The abundant intrinsic defects in OSs promote ohmic contact formation but adversely affect the Schottky barrier interface, especially in OSs with diverse sub-bandgap states, such as amorphous indium–zinc oxide (a-IZO). This study introduces an ultrathin alumina (Al2O3) interlayer, deposited via plasma-enhanced atomic layer deposition (PEALD), to effectively reduce interface defects and metal-induced gap states (MIGSs) between a-IZO and the platinum (Pt) anode. The top-anode a-IZO Schottky barrier diode (SBD) demonstrates a Schottky barrier height ( $\Phi _{\text {B}}$ ) of 0.73 eV and an ideality factor (n) of 1.35. Such ultrathin Al2O3 engineering effectively enhances the feasibility of high-quality OS Schottky contact.