Nearly Constant Electrical Resistance over Large Temperature Range in Cu(3)NM(x) (M = Cu, Ag, Au) Compounds

Electrical resistance is a material property that usually varies enormously with temperature. Constant electrical resistivity over large temperature range has been rarely measured in a single solid. Here we report the growth of Cu(3)NM(x) (M = Cu, Ag, Au) compound films by magnetron sputtering, aiming at obtaining single solids of nearly constant electrical resistance in some temperature ranges. The increasing interstitial doping of cubic Cu(3)N lattice by extra metal atoms induces the semiconductor-to-metal transition in all the three systems. Nearly constant electrical resistance over 200 K, from room temperature downward, was measured in some semimetallic Cu(3)NM(x) samples, resulting from opposite temperature dependence of carrier density and carrier mobility, as revealed by Hall measurement. Cu(3)NAg(x) samples have the best performance with regard to the range of both temperature and doping level wherein a nearly constant electrical resistance can be realized. This work can inspire the search of other materials of such a quality.