High-Voltage a-IGZO TFTs With the Stair Gate-Dielectric Structure

Abstract

In this work, a high-voltage amorphous In-Ga-Zn-O (a-IGZO) thin-film-transistors (TFTs) with the stair gate-dielectric at the drain side were demonstrated. The electrical properties of the proposed TFTs were comprehensively investigated. The breakdown voltage (V $_{BD}$ ) was significantly enhanced, and the V $_{BD}$ of over 60 V is achieved in the TFT with the stair length (L $_{stair}$ ) of 3 μm. The TCAD simulation and emission microscope (EMMI) measurements are performed to reveal the working and breakdown mechanisms of the proposed stair gate-dielectric TFTs. The descending electron current density in the channel lowers the stair-gate TFTs' on-current. Meanwhile, the stair-gate-dielectric region endures a strong electric field and improves the V $_{BD}$ of the device. Finally, the exponential trade-off relationship between the V $_{BD}$ and the on-state resistance (R $_{on}$ ) was established.