Delamination of Graphene/ZnO interlayer driven by photocatalytic effect for flexible a-IGZO TFT applications

In the study, we report a novel polyimide (PI) delamination process using thermally reduced graphene oxide (rGO) and a Zinc Oxide (ZnO) photocatalyst as a De-Bonding Layer (DBL). The role of rGO was to control the adhesion force between the carrier glass and PI film. The ZnO nanoparticle (NP) was used as a photocatalyst to promote the chemical reaction between reduced graphene oxide and the atmosphere. The adhesion force was reduced safely and reproducibly between the carrier glass and the PI under ultraviolet (UV, 385 nm wavelength) irradiation environment, and the optimal rGO and ZnO NP concentration were 0.8 mg/ml and 15 mM, respectively. Finally, amorphous InGaZnO (a-IGZO) TFT was fabricated on the PI substrate with rGO/ZnO NP to confirm the effect of the UV irradiation process on the reliability of the backplane. The a-IGZO TFTs on Glass/rGO/ZnO/PI exhibit the following parameters; Vth: 0.60 ± 0.12 V, µFE: 16.60 ± 0.71 cm2/Vs, and SS: 0.31 ± 0.01. After the dry delamination, there was no significant change in the a-IGZO TFT performance (ΔµFE: 0.17 cm2/Vs, ΔVth: 0.24 V, ΔS·S: 0.00) as well as less than ΔVth less than 0.3 V under the negative/positive bias temperature stability condition (VGS=±20 V, 60 °C, and 10,000sec)).