Effects of low-temperature annealing in nitrogen atmosphere on elevated-metal metal-oxide (EMMO) thin-film transistors (TFTs) are investigated and reported in this article. Compared with the short-circuit behavior of EMMO TFTs after annealing in nitrogen atmosphere at 300 °C, it is found that TFTs received annealing in nitrogen atmosphere at 200 °C prior to that at 300 °C not only remain the transfer characteristics, but also exhibit improved on-state current and subthreshold characteristics. Both the results of X-ray photoelectron spectroscopy (XPS) and persistent photoconductivity (PPC) confirmed the reduction of oxygen vacancies in the a-IGZO after annealing in nitrogen atmosphere at 200 °C, indicating that the passivation of oxygen vacancy with nitrogen is dominant rather than the generation of oxygen vacancy. Furthermore, the thermal stability improvement could not be realized when the annealing in nitrogen atmosphere at 200 °C was performed before the source/drain formation annealing at 400 °C, which emphasizes the importance of annealing procedures during device fabrication.

Different from the conventional degradation phenomenon under positive bias stress (PBS), the shift of the transfer characteristic curve of polycrystalline silicon thin-film transistors (TFTs) to the negative gate bias direction after PBS is observed and reported. The PBS degradation is found to be recoverable and the recovery proceeds at a faster rate first and then continues at a much slower rate. The recovery can be further accelerated at a higher temperature or by applying a negative gate bias. After detailed data analysis, the degradation mechanism is proposed to be the generation of protons in the gate oxide and its accumulation at the channel/gate oxide interface. The proposed degradation model could explain both the degradation phenomena and the recovery behaviors of PBS degradation.

In this letter, the carrier mobility of amorphous InGaZnO (a-IGZO) thin-film transistor (TFT) was remarkably enhanced by the introduction of nitrogen and the formation of Zn3N2, in which the saturation field-effect mobility ( $\mu _{\text {sat}}$ ) was 61.6 cm2/Vs. Annealing temperature plays a key role on the enhancement of carrier mobility. When the annealing temperature was increased to 400 °C, $\mu _{\text {sat}}$ was reduced to 4.1 cm2/Vs, which was proposed to be due to the formation of defective ZnxNy based on X-ray photoelectron spectroscopy results. In addition, the a-IGZO TFT with enhanced mobility did not exhibit persistent photoconductivity behavior. The high carrier mobility could expand the application of a-IGZO TFTs to functional circuits in active-matrix displays.

The reliability of p-type excimer laser annealing (ELA) poly-Si thin-film transistor (TFTs) under respective pulse gate and drain bias stresses is investigated in this paper. Under the bipolar gate pulse stress, the device exhibits increased on-state current and the degradation is dominated by the dynamic mechanism. Under the negative drain pulse stress, the device also exhibits increased on-state current, but the degradation is dominated by the DC mechanism. Explanations to the observed degradation phenomena are proposed.