Metallic Conduction in NiS2 Nanocrystalline Structures

Thermolysis of Ni butanethiolate in a sulfur atmosphere has been carried out at 300 and 600 degrees C to produce NiS2 nanocrystalline films with mean crystallite sizes of 16 and 192 nm and resistivity values of similar to 451 and 3540 mu Omega.m, respectively; the resistivity values are similar to 2 orders of magnitude less compared to the bulk value (12000 mu Omega.m). This is a significant observation since NiS2 is an insulator in the bulk. Combining electrostatic force microscopy, transport, and surface degradation experiments, we establish conclusively that the surface layer of NiS2 is metallic. The density of the surface conduction states computed through the variable range hopping model is found to be comparable to the bulk density of states of good metals. The precursor is also amenable for patterning by electron beam and molding.