Highly Stable ZnON Thin-Film Transistors With High Field-Effect Mobility Exceeding 50 cm(2)/Vs

Abstract

High-performance thin-film transistors (TFTs) based on ZnON channels were fabricated using a de reactive sputtering method. To improve the photoinduced bias stability, a postannealing process was carried out at a low ambient pressure (similar to 100 mTorr, air ambient) at 250 degrees C for various annealing times (1-5 h). The transfer characteristics of the postannealed ZnON TFTs exhibited an improved subthreshold swing ranging from 0.60 to 0.42 V/decade. Other transport properties remained similar including a high mobility (mu(sat)) of >50 cm(2)Ns, a threshold voltage (Vth) of 2.5 V, and an ON OFF drain current ratio of >10(8). In addition, photoinduced bias reliability under a gate bias stress (V-G = 20 V) was significantly improved from -10.88 V (1 h) to -2.28 V (5 h). These results can be explained by the enhancement of bonding properties between Zn metal and two different anions (O, N) as stable N Zn O states.