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

Abstract

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-kappa gate dielectrics. In this study, we systematically investigate the impact of high-kappa 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 kappa 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-kappa gate dielectrics to enhance drive current.