Enhancing InGaZnO transistor current through high-κ dielectrics and interface trap extraction using single-pulse charge pumping

Enhancing the drive current of oxide semiconductor transistors is crucial for enabling high-resolution displays with thin bezels and improving memory write and access speeds. High-mobility channel materials boost drive current but typically require stricter process control and reliability, presenting mass-production challenges compared to stable materials like InGaZnO. Therefore, increasing drive current without changing the channel material is a desirable goal to pursue. One approach is to enhance gate capacitance using high-κ gate dielectrics. In this study, we systematically investigate the impact of high-κ gate dielectrics on the performance of InGaZnO transistors, focusing on three different gate insulators: SiO₂, HfO₂, and ZrO₂. Experimental results show that as the dielectric constant increases from 3.9 (SiO₂) to 17 (HfO₂) and 30 (ZrO₂), the drive current is enhanced by factors of 2.8 and 7, respectively–less than the expected enhancement from κ alone. Device simulations reveal that contact resistance, channel capacitance, and interface trap density all influence the drive current. Notably, interface traps emerge as the primary limiting factor, particularly in HfO₂, significantly degrading the transconductance. Utilizing the single-pulse charge pumping method, we quantify interface trap densities and demonstrate that reducing interface traps is essential in fully leveraging high-κ gate dielectrics to enhance drive current.