Realization of highly transparent and low resistance TiO2/Ag/TiO2 conducting electrode for optoelectronic devices

Abstract The effect of TiO 2 thickness on the optical and electrical properties of TiO 2 /Ag/TiO 2 multilayer films deposited on glass substrates was investigated. The as-deposited TiO 2 samples were found to be amorphous. The transmission window became wider and gradually shifted toward lower energies as the TiO 2 thickness increased from 10 to 50 nm. In particular, the TiO 2 /Ag/TiO 2 (40 nm/18.8 nm/40 nm) multilayer film exhibited a transmittance of ~ 95% at 550 nm. Incrementally increasing the TiO 2 thickness to 50 nm gradually decreased the carrier concentration to 6.1×10 21 cm −3 , while the charge mobility varied from 22.3 to 20.4 cm 2 V −1 s −1 . In addition, when increasing the TiO 2 thickness to 50 nm, the samples showed similar sheet resistances of 3.9–4.4 Ω/ □ , but the resistivity increased by a factor of 3.8. Haacke׳s figure of merit (FOM) was calculated for the samples and plotted as a function of TiO 2 thickness; the TiO 2 (40 nm)/Ag (18.8 nm)/TiO 2 (40 nm) multilayer yielded the highest FOM of 159.9×10 −3 Ω −1 .