Solar cells with silicon oxynitride dielectric layers and methods of forming silicon oxynitride dielectric layers for solar cell fabrication are described. For example, an emitter region of a solar cell includes a portion of a substrate having a back surface opposite a light receiving surface. A silicon oxynitride (SiO.sub.xN.sub.y, 0<x, y) dielectric layer is disposed on the back surface of the portion of the substrate. A semiconductor layer is disposed on the silicon oxynitride dielectric layer.
 The invention described herein was made with Governmental support under contract number DE-FC36-07G017043 awarded by the United States Department of Energy. The Government may have certain rights in the invention.