NOVELTY - Method of forming a solar cell (200), comprises: forming a photoelectric unit (214) on a substrate (114); forming a back contact layer on the substrate; and forming a transition layer (218) between the photoelectric unit and the back contact layer.    USE - The method is useful for producing solar cells, which is useful for converting sunlight into direct current electrical power.    ADVANTAGE - The transition layer formed by the method has a refractive index lower than either the photoelectric unit or the back contact layer. The method improves efficiency of solar cells by improving light capture between the photoelectric unit and back reflector. The method forms a transparent conductive film with high transmittance suitable for solar cell devices. The method produces a transition layer that improves light capture at the back contact layer without adding absorption. The transition and transparent conductive oxide layers efficiently increase the photoelectric conversion efficiency and device performance of the solar cell as compared to conventional methods. The transparent conductive film has high optical transmittance in the visible or higher wavelength region to facilitate transmitting sunlight into the solar cells without adversely absorbing or reflecting light energy.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) forming a transparent conductive layer, comprising supplying a gas mixture comprising at least one of nitrogen and excess oxygen to a processing chamber, sputtering a source material from a target comprising zinc in the processing chamber and reacting the source material with the gas mixture to deposit a transparent conductive layer comprising at least one of nitrogen and excess oxygen; and    (2) a solar cell device, comprising a photoelectric unit, a transmitting conducting layer adjacent to the photoelectric unit and a transition layer comprising silicon and at least one of oxygen and nitrogen between the photoelectric unit and the transmitting conducting layer.    DESCRIPTION OF DRAWING(S) - The figure shows a cross sectional view of a thin film solar cell.    Substrate (114)    Solar cell (200)    Transparent conductive oxide layer (202)    Photoelectric unit (214)    Transition layer. (218)