We investigated the electrical performance and positive bias stress (PBS) stability of the amorphous InGaZnO thin-film transistors (a-IGZO TFTs) with SiOx passivation layers after the post-annealing treatments in different atmospheres (air, N2, O2 and vacuum). Both the chamber atmospheres and the device passivation layers proved important for the post-annealing effects on a-IGZO TFTs. For the heat treatments in O2 or air, the larger threshold voltage (VTH) and off current (IOFF), smaller field-effect mobility (μFE), and slightly better PBS stability of a-IGZO TFTs were obtained. The X-ray photoemission spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS) measurement results indicated that the oxygen atoms from the ambience led to less oxygen vacancies (VO) and more oxygen-related defects in a-IGZO after the heat treatments in O2 or air. For the annealing processes in vacuum or N2, the electrical performance of the a-IGZO TFTs showed nearly no change, but their PBS stability evidently improved. After 4500 seconds’ stressing at 40 V, the VTH shift decreased to nearly 1 V. In this situation, the SiOx passivation layers were assumed to effectively prevent the oxygen diffusion, keep the VO concentration unchanged and refuse the oxygen-related defects into the a-IGZO films.

We investigated the ultraviolet (UV) light detectors of amorphous InGaZnO thin film transistors (a-IGZO TFTs) with doublestacked channel layers (DSCL). When the UV light wavelength decreased from 400 nm to 370 nm, the devices with DSCL exhibited better light response properties than those with single channel layers. Especially, the a-IGZO TFT with DSCL (OR-IGZO/OD-IGZO) structure achieved 28.6 dB of sensitivity, 9.7×10 -7 A/W of responsivity, and 1.6×10 8 cm•Hz 0.5 •W -1 of detectivity under the UV light with wavelength = 370 nm. This improvement was assumed to the best combination of light absorption and interface states for the special DSCL structure.

Amorphous InGaZnO thin film transistors (a-IGZO TFTs) with double-stacked channel layers (DSCL) were quite fit for ultraviolet (UV) light detection, where the best DSCL was prepared by the depositions of oxygen-rich (OR) IGZO followed by the oxygen-deficient (OD) IGZO films. We investigated the influences of oxygen partial pressure (PO) for DSCL-TFTs on their sensing abilities by experiments as well as Technology Computer Aided Design (TCAD) simulations. With the increase in PO values for the DSCL depositions, the sensing parameters, including photogenerated current (Iphoto), sensitivity (S), responsivity (R), and detectivity (D*) of the corresponding TFTs, apparently degraded. Compared with PO variations for the OR-IGZO films, those for the OD-IGZO depositions more strongly influenced the sensing performances of the DSCL-TFT UV light detectors. The TCAD simulations showed that the variations of the electron concentrations (or oxygen vacancy (VO) density) with PO values under UV light illuminations might account for these experimental results. Finally, some design guidelines for DSCL-TFT UV light detectors were proposed, which might benefit the potential applications of these novel semiconductor devices.

A novel reading circuit based on amorphous InGaZnO thin film transistors (a‐IGZO TFTs) for flexible flash memories is proposed in this paper. The circuit contains only active devices in order to narrow its layout size; in addition to the main part, the scanning circuit and output buffer are designed for practical applications. The simulation results show its good stability and strong resistance to the design and processing variations of a‐IGZO TFTs.

We proposed a novel 6T1C pixel circuit as well as its driving scheme based on amorphous InGaZnO thin‐film transistors (a‐IGZO TFTs) for micro‐LED displays. Compared with the conventional 7T1C pixel circuit, the new design not only simplified the circuit structure but also exhibited apparently better threshold voltage compensation effect as well as much lower flicker value.