UV-Ozone Process for Film Densification of Solution-Processed InGaZnO Thin-Film Transistors

Abstract

The effects of ultraviolet (UV)-ozone treatment on solution-processed amorphous InGaZnO (IGZO) thin-film transistors (TFTs) grown using the sol-gel method are investigated. The UV-ozone-treated TFT devices showed an improved field-effect mobility of 1.52 cm V s and a subthreshold slope (S) of 0.42 V/dec compared to those of IGZO TFT devices with only thermal annealing (0.75 cm V s and 0.84 V/dec, respectively). The enhancement of the UV-ozone-treated TFTs is mostly attributed to the increased film packing density, higher Al S/D electrodes adhesion properties, reduced oxygen-related defects, and less electron trapping of the IGZO thin films, which improved the TFT performance and bias stress stability.Index Terms-Amorphous InGaZnO (IGZO), sol-gel, ultraviolet (UV)-ozone.

Deep-UV-Enhanced Approach for Low-Temperature Solution Processing of IZO Transistors with High-k AlOx/YAlOx Dielectric

“…However, it led to a little degradation of the semiconductor characteristics, marginally reducing the mobility and causing a slight increase of SS (from 91 to 149 mV dec –1 ) (Figure b). This observation may be associated with the structural damage in the IZO channel, induced by the excessive DUV exposure, or to a partial increase of the trap density at the semiconductor–dielectric interface …”

“…However, it led to a little degradation of the semiconductor characteristics, marginally reducing the mobility and causing a slight increase of SS (from 91 to 149 mV dec −1 ) (Figure 4b). This observation may be associated with the structural damage in the IZO channel, induced by the excessive DUV exposure, 52 or to a partial increase of the trap density at the semiconductor−dielectric interface. 53 Similarly, the role of the post-annealing time was investigated through the characterization of TFTs exposed for 45 min to DUV light and subsequently treated with variable post-annealing periods (0−120 min).…”

Protein Biophotosensitizer-Based IGZO Photo-thin Film Transistors for Monitoring Harmful Ultraviolet Light

“…As mentioned earlier, the UVO treatment reduces the defective V O , which results in the Fermi level shifting farther from the conduction band edge. 41,42 Consequently, energy band bending can be induced at the interface between the UVA-IGZO and A-IGZO layers because the A-IGZO layer is relatively rich in V O sites compared to the UVA-IGZO layer (see also the energy band alignment under an equilibrium state in Figure S9, Supporting Information). For the A-IGZO film, which is more defective than the UV-IGZO film, charge trapping at the interfaces between UVA-IGZO/A-IGZO/air can be caused by trap sites shown in the band diagram of Figure 2 (Figures S9 and S10, Supporting Information).…”

Reducing the Persistent Photoconductivity Effect in Zinc Oxide by Sequential Surface Ultraviolet Ozone and Annealing Treatments

“…25,26 The ultraviolet ozone (UVO) treatment helps to reduce the V O and increase the metal hydroxides groups on the ZnO surface by converting adsorbed O 2 − to OH − . 27,28 Finally, postannealing treatment was adopted to improve the film quality by making the film densely and inducing zinc−oxygen bonding in the film. 29,30 Thus, a ZnO phototransistor fabricated by sequential surface treatment shows superior photoresponse characteristics.…”