A method of forming a thin film including vaporizing a nickel compound on a substrate using a heterostructured nickel compound including a nickel amidinate ligand and an aliphatic alkoxy group and providing a vapor containing the vaporized nickel compound onto the substrate, thereby forming a nickel-containing layer. Vaporizing the nickel compound on the substrate is performed in an atmosphere in which at least one selected from plasma, heat, light, and voltage is applied.