Enhanced On-State Current and Stability in Heterojunction ITO/ZnO Transistors: A Mechanistic Analysis

The growing demand for high-performance oxide transistors in advanced integrated circuits (ICs) underscores the need for innovative device structures, with heterojunctions emerging as a promising approach. This study presents high-performance ITO/ZnO transistors, which outperform individual ITO or ZnO transistors by achieving an on-state current of 19.2 μA/μm at a drain voltage of 1 V and exhibiting a minimal threshold voltage shift of -0.16 V under negative bias illumination stress. Band structure analysis reveals that the differences in the conduction band minimum and Fermi level between the ZnO and ITO films lead to the formation of a potential well at the ITO/ZnO interface. Furthermore, the increase in the on-state current is attributed to electron confinement at the ITO/ZnO interface, while the enhanced NBIS stability is ascribed to both the band structure and ZnO passivation. These findings make significant contributions to both optimizing the performance and analyzing the mechanisms of oxide devices, highlighting the potential of high-performance ITO/ZnO transistors in 3D integrated circuits, advanced memory devices, and back-end-of-line (BEOL) processes.