NOVELTY - The substrate and superstrate type thin film solar cell (10) comprises a sheet-shaped transparent substrate (11), an absorber layer (12) disposed over the substrate, an ohmic contact layer (13) disposed between the substrate and the absorber layer, and a transparent conductive layer (14) disposed on the absorber layer and configured so that light enters the solar cell through the transparent conductive layer. The ohmic contact layer includes a lower ohmic contact layer and/or an upper ohmic contact layer each including the ruthenium layer having a thickness of 1-50 nm.    USE - The substrate and superstrate type thin film solar cell is useful for converting light to electrical energy (all claimed), where the solar cell is photovoltaic device.    ADVANTAGE - The substrate and superstrate type thin film solar cell can be economically manufactured with high throughput and quality, enhanced cell efficiency, increased optical reflection, good mechanical, structural, compositional and electrical properties and long term stability and without lattice mismatch.    DETAILED DESCRIPTION - The substrate and superstrate type thin film solar cell (10) comprises a sheet-shaped transparent substrate (11), an absorber layer (12) disposed over the substrate, an ohmic contact layer (13) disposed between the substrate and the absorber layer, and a transparent conductive layer (14) disposed on the absorber layer and configured so that light enters the solar cell through the transparent conductive layer. The ohmic contact layer includes a lower ohmic contact layer and/or an upper ohmic contact layer each including the ruthenium layer having a thickness of 1-50 nm. The upper ohmic contact layer is sandwiched between the absorber layer and the lower ohmic contact layer. The sheet-shaped transparent substrate is a glass, a stainless steel sheet and/or an aluminum sheet, and an insulating sheet. The transparent conductive layer is a cadmium sulfide/zinc oxide stack. The absorber layer is a group IBIIIAVIA compound layer. The lower ohmic contact layer is molybdenum layer, chromium layer and copper layer with a thickness of 100-1000 nm, tantalum layer, tungsten layer, nickel layer, aluminum layer, and titanium layer formed on the sheet shaped substrate. INDEPENDENT CLAIMS are included for:    (1) a method of making a solar cell; and    (2) a method of forming a copper indium gallium selenium sulfide absorber layer.    DESCRIPTION OF DRAWING(S) - The diagram shows a cross-sectional view of a solar cell.    Solar cell (10)    Substrate (11)    Absorber layer (12)    Contact layer (13)    Transparent layer (14)    Radiation. (15)