Noble-Metal-Free, Polarity-Switchable IGZO Schottky Barrier Diodes

In this work, noble-metal-free, polarity-switchable indium-gallium-zinc oxide (IGZO) Schottky barrier diodes (SBDs) with a vertically stacked structure of copper (Cu)/AlOx/IGZO/indium-tin oxide (ITO) were demonstrated for the first time. The polarity of the SBDs can be manipulated through a simple postannealing process in $\text{N}_{{2}}$ . Without annealing, the as-fabricated IGZO SBD works in a negative operation mode (i.e., the dominating current flow direction is from the bottom ITO electrode to the top Cu electrode). The optimized SBD working in the negative mode exhibits excellent electrical properties with a rectification ratio of $2.12\times 10^{6}$ , a Schottky barrier height of 0.87 eV, and an ideality factor of 1.26. After annealing in $\text{N}_{{2}}$ , the IGZO SBD switches to a positive operation mode. Through optimization, the positive SBD exhibits a rectification ratio of $4.24\times 10^{5}$ , a Schottky barrier height of 0.83 eV, and an ideality factor of 1.43. The mechanism of polarity inversion behavior for the IGZO SBDs was discussed in detail by taking the Cu diffusion and contact modification via the AlOx inserting layer into account. This work sheds light on the development of noble-metal-free metal oxide (MO) SBDs with controllable polarities and the future integration of MO SBDs with other electron devices.