High-Vacuum Codeposition of Niobium Nitride

A technique has been developed for the reactive high-vacuum codeposition of niobium nitride at rates in excess of several hundred Å/sec. With gaseous ammonia as the nitrogen source, films with transition temperatures in excess of 13°K have been fabricated. The depression of the transition temperature from values reported for sputtered films is attributed to ammonia decomposition chemistry. In addition, 4.2°K critical currents in excess of 106 A/cm2 have been measured for 1-μ-thick films.