Electrical and optical properties of zinc-oxide films deposited by the ion-beam sputtering of an oxide target

The influence of the parameters of the deposition process on the stoichiometric composition and electrical and optical properties of ZnO films deposited by the ion-beam sputtering of a ZnO target is studied. It is established that, upon sputtering of a ZnO target with stoichiometric composition, there is a deficit of oxygen in the films deposited. Even for the case of target sputtering in a pure O$_2$ atmosphere, the stoichiometry index of the films is no higher than 0.98. A decrease in the oxygen content in the films is accompanied by a sharp decrease in the resistivity to 35–40 $\Omega$ m, narrowing of the optical band gap, and a shift of the optical transmittance edge from 389 to 404 nm. All of the variations in the optical and electrical properties of the ZnO films can be attributed to variations in the concentration and mobility of free charge carriers in the films.