Analysis of Improved Performance Under Negative Bias Illumination Stress of Dual Gate Driving a- IGZO TFT by TCAD Simulation

Abstract

We report the numerical simulation of the effect of a dual gate (DG) TFT structure operating under dual gate driving on improving negative bias illumination stress (NBIS) of amorphous indium gallium zinc oxide thin-film transistors (a-IGZO TFTs). With respect to the transfer characteristics of a-IGZO TFTs, we show a larger negative threshold voltage shift ( $\Delta V_{\mathrm {TH}})$ with increasing a-IGZO active layer thickness. This trend is confirmed by TCAD simulation, where the initial transfer curve is plotted under varying a-IGZO thickness keeping a constant density of states. Under varying a-IGZO thickness, TCAD simulation results confirm TFTs under DG driving shows significantly less $\Delta V_{\mathrm {TH}}$ shift under NBIS compared with that of single gate (SG) driving TFTs. Under 10 K seconds of NBIS, TCAD simulation results show the increase in donor-like states ( $N_{\mathrm {GD}})$ by $5.25 \times 10^{17}$ cm $^{\mathrm {-3}}$ eV $^{\mathrm {-1}}$ and acceptor-like states ( $N_{\mathrm {GA}})$ by $7.5\times 10^{16}$ cm $^{\mathrm {-3}}$ eV $^{\mathrm {-1}}$ .