Ohmic contacts to SnS films: Selection and estimation of thermal stability

Selection of Ohmic contacts to SnS films is one of the crucial tasks for the fabrication of efficient SnS devices. Thus, we examined different nonalloyed metallization schemes, namely, Ag, Al, In, and Sn to SnS films since their Fermi level pins exactly in between the conduction and valance bands of SnS. To explore the Ohmic behavior of M/SnS (M=Ag, Al, In, Sn) structures, the electrical properties of as-grown structures have been studied at different temperatures. From these studies it is noticed that at room temperature all M/SnS structures, except Ag/SnS, have an excellent Ohmic behavior over the voltage range from -10 to 10 V. However, Ag/SnS structures showed Ohmic trend only in the voltage range of +/- 6 V. The stability of the M/SnS structures was also examined by annealing them at different temperatures (300-500 degrees C) and the obtained peculiar results are reported.