In situ growth of SnS absorbing layer by reactive sputtering for thin film solar cells

The semiconductor SnS is a promising candidate for low cost earth-abundant photovoltaic absorbing layers and presents some interesting challenges in single phase material preparation. An in situ growth process via reactive sputtering was employed in this work to fabricate SnS thin films. The effect of growth temperature on the properties of prepared films was investigated to obtain phase-pure SnS. It is revealed that the films grown at 400 degrees C presented a single orthorhombic SnS phase with a direct optical band gap of 1.14 eV, a high optical absorption coefficient above 9.0 x 10(4) cm(-1), and a p-type conductivity with a high carrier concentration around 10(17) cm(-3). The associated device with a structure of ITO/i-ZnO/CdS/SnS/Mo/glass achieves a power conversion efficiency of 0.26%. Based on the TEM characterization, the limiting factors for SnS device performance are revealed and discussed.