Photovoltaic cell and method of its manufacture

A method is presented for use in manufacture of a semiconductor device, such as a photovoltaic cell. The method comprises: providing a structure comprising a ZnO layer; applying a surface treatment to said structure for a certain time period to form a layer of ZnS on said ZnO layer; and depositing an active structure on said ZnS layer. The active structure may be a light absorbing structure, including a light absorbing semiconductor or a molecular light absorbing dye. The provision of the ZnS buffer layer between the ZnO layer and the active structure improves the device performance.