Steep Subthreshold Swing and Enhanced Illumination Stability InGaZnO Thin-Film Transistor by Plasma Oxidation on Silicon Nitride Gate Dielectric

In this paper, an InGaZnO thin-film transistor (TFT) based on plasma oxidation of silicon nitride (SiN(x)) gate dielectric with small subthreshold swing (SS) and enhanced stability under negative bias illumination stress (NBIS) have been investigated in detail. The mechanism of the high-performance InGaZnO TFT with plasma-oxidized SiN(x) gate dielectric was also explored. The X-ray photoelectron spectroscopy (XPS) results confirmed that an oxygen-rich layer formed on the surface of the SiN(x) layer and the amount of oxygen vacancy near the interface between SiN(x) and InGaZnO layer was suppressed via pre-implanted oxygen on SiN(x) gate dielectric before deposition of the InGaZnO channel layer. Moreover, the conductance method was employed to directly extract the density of the interface trap (D(it)) in InGaZnO TFT to verify the reduction in oxygen vacancy after plasma oxidation. The proposed InGaZnO TFT with plasma oxidation exhibited a field-effect mobility of 16.46 cm(2)/V·s, threshold voltage (V(th)) of −0.10 V, I(on)/I(off) over 10(8), SS of 97 mV/decade, and V(th) shift of −0.37 V after NBIS. The plasma oxidation on SiN(x) gate dielectric provides a novel approach for suppressing the interface trap for high-performance InGaZnO TFT.