Room temperature deposited silver oxide films by dc magnetron sputtering with high sputtering power: effect of deposition time on microstructure, electrical and optical properties

Abstract

A series of non-stoichiometric p-type silver oxide (AgxO) films are room temperature deposited on glass substrates at different deposition time (td) by dc magnetron sputtering with high sputtering power. The evolution in component and the change in electrical and optical properties of the films with td are studied by XRD, SEM, EDS, visible-infrared spectroscopy and Hall data. The p-type conduction of cubic AgO and Ag2O phases is also proposed in mechanism. The evolution in component from AgO to almost Ag2O and the change in microstructure with td are caused by the thermal decomposition of AgO phase induced by high sputtering power. The film’s absorption edge firstly redshifts from 2.8 to 2.3 eV with increase of td from 2 min to 15 min, and then is suddenly reduced to 1.25 eV of cubic phase Ag2O at 20 min td. The phases AgO and Ag2O both have p-type conduction characteristics, mainly due to the Ag vacancies and O vacancies, respectively. The free carrier concentration and the resistivity of the films are both increased and reduced with increase of td. The AgxO film with 15 min td is the highest in p-type conduction ability due to the highest free carrier concentration and mobility, and thus is capable of being the candidate of hole-transporting layer materials of perovskite solar cells.