A method of reactively sputtering from a metallic zinc target a transparent conductive oxide electrode of zinc oxide from a metallic zinc in a silicon photo diode device and the resultant product, such as a solar cell. The electrode in deposited on a transparent substrate in at least two steps. The oxygen partial pressure is reduced in the first step to produce an oxygen-deficient ZnO layer, which is highly conductive and has a textured surface, and is increased in the second step to produce a more stoichiometric ZnO, which has a refractive index more closely matched to the overlying silicon device. The second layer is substantially thinner than the first so the surface texture is transferred across it and the overall sheet resistance of the stack structure is reduced.