Abstract
The growth of stoichiometric samples of thermally unstable nobleโmetal nitrides remains a challenge. Thin films of nearly stoichiometric Cu~3~N have been successfully grown on Si (100) wafers by reactive magnetron sputtering of Cu target with mixed nitrogen and argon. The controversies regarding bandgap, lattice constant, decomposition temperature, roomโtemperature electrical resistivity, etc., can be resolved. Nitrogen reโemission leads to the formation of Cu~3~N nanocrystallites, generally 40โ60โnm in size, enclosed by Cuโterminated {111} facets. Samples with a slight Cu excess may turn into a metallic conductor with excellent electrical conductivity via a percolation mechanism. Unfavorable growth conditions may give rise to blistering or even mesocaled fivefold symmetrical relief structures in the deposit. These structures result from the rearrangement of nanocrystals via gliding along the {111} facets. Ternary Cu~3~NM~x~ (Mโ=โPd, Cu, In, Zn, etc.) compounds, with the excessive metal atoms occupying the cell centers of the Cu~3~N lattice, can be obtained by cosputtering under similar conditions. Such ternary compounds can easily be made metallic. In Cu~3~NPd~0.238~ a constant electrical resistivity was measured in a temperature range โผ200โK. Incorporation of In or O atoms may raise the decomposition temperature but not to more than 400โยฐC if the decomposition products are required to be as good a conductor as Cu. The present results might be relevant for growing films of thermally unstable materials. The peculiar electrical conduction behavior in the Cu~3~NM~x~ structures is expected to inspire the search for nearly zeroโband materials similar to Cu~3~NPd~0.238~ as well as to promote an indepth exploration of potential applications of these materials.