Effects of thin titanium and graphene depositions and annealing temperature on electrical, optical, and mechanical properties of IGZO/Ti/graphene/PI specimen

Abstract

High-quality monolayer graphene produced on copper foil using the chemical vapor deposition method, was transferred to a polyimide (PI) substrate to improve the electrical and mechanical properties of IGZO/Ti/graphene/PI specimens. Ti film was deposited as the interlayer to protect the graphene layer during the IGZO deposition and improve the adhesion strength between the IGZO film and the graphene/PI substrate. Significant increases in hardness (H) and reduced modulus (Er) and a great reductions in sheet resistance and resistivity are obtained when the pattern integrity and microstructure of the graphene layer were remained after the IGZO deposition. The X-ray diffraction (XRD) intensity and grain size of InGaO3(ZnO)3 (0012) increase with increasing the annealing temperature and using the graphene layer. Annealing temperature rise can reduce the residual tensile stress, but also the hardness, and reduced modulus. Using graphene film as the interlayer and increasing the annealing temperature greatly reduced sheet resistance and resistivity, but significantly increased carrier mobility and concentration compared to those for a specimen without graphene. Burstein-Moss effect is exhibited in the specimens such that both the apparent optical energy gap (Eg) and carrier concentration are elevated by raising the temperature, irrespective of the use of graphene. The effects of annealing temperature and graphene on the optical properties exhibited in the seven colors were also evaluated.