Growth parameters and crystal morphology of vapor-deposited niobium nitride

Abstract

Some crystal forms of niobium nitride were obtained on a graphite substrate by Chemical Vapor Deposition (CVD) using a reactant gas mixture composed of NbCl₅, N₂, H₂ and Ar. Growth parameters affecting the deposition rate, the structure and composition of the deposited species and the crystal morphology were investigated in detail. A mixed phase of Nb₂N and Nb₄N₃ or Nb₄N₃ and NbN tended to deposit on the substrate at temperatures of 1150°–1300°C. A single phase of cubic NbN, however, can be obtained at a temperature higher than 1350°C using a mixture mole ratio of N₂/NbCl₅ of above 45 and a H₂ flow rate higher than 3.5 ml/sec. A linear relationship was found between the weight of NbN deposit and the reaction time. Crystal forms of uniform coatings, whiskers, dendrites, polyhedrons and blades of niobium nitride were grown at various temperatures and feed gas flow rates.