Eco-friendly and efficient rectifying p-n diodes have been developed by using cost-effective and non-toxic fin monosulfide (SnS) thin films. Chemically stoichiometric fin monosulfide (SnS) thin films followed by titanium/gold (Ti/Au) bilayer contacts were deposited on Si substrates and then, the structures were treated by rapid thermal annealing process (RTP) at different temperatures. The impact of RTP treatment on the surface morphology and chemical composition of Ti/Au contacts and SnS films along with their electrical characteristics were investigated. The electrical measurements show that as compared to untreated Si/SnS/Ti/Au structures, the heat-treated structures typically at 200 degrees C possess low electrical resistivity and contact resistance of similar to 3 x 10(-2) Omega cm and similar to 11 k Omega, respectively. Heterojunction formed between p-SnS and n-Si exhibited excellent diode characteristics and possess a high current flow in the order of milliamperes, and excellent rectification factor of 1177@ 5 V.