Highly flexible Al-doped ZnO/Ag/Al-doped ZnO multilayer films deposited on PET substrates at room temperature

Abstract We investigated the effects of the Ag layer thickness on the electrical and optical properties of AZO (36 nm)/Ag/AZO (36 nm) multilayer films that were deposited on polyethylene terephthalate (PET) substrates using a radio frequency magnetron sputtering method. The AZO/Ag/AZO films had transmittances over 74–89% at 550 nm. The relationship between the transmittance and the Ag layer thickness was investigated with three-dimensional finite-difference time-domain (3D FDTD) simulations to understand high transmittance. As the Ag layer thickness increased from 15 to 23 nm, the carrier concentration increased from 5.84×10 21 to 9.66×10 21 cm −3 , while the sheet resistance decreased from 10.15 to 3.47 Ω sq −1 . The Haacke figure of merit (FOM) was calculated for the samples with various Ag layer thicknesses; it was a maximum at 19 nm (43.9×10 −3 Ω −1 ). The resistance change for the 100 nm-thick ITO only films was unstable even after 5 cycles, while that of the AZO (36 nm)/Ag (19 nm)/AZO (36 nm) film remained constant up to 1000 cycles.