Effects of substrate temperature on properties of NbNx films grown on Nb by pulsed laser deposition

WOS: 000297265200056NbNx films were deposited on Nb substrate using pulsed laser deposition. The effects of substrate deposition temperature, from room temperature to 950 degrees C, on the preferred orientation, phase, and surface properties of NbNx films were studied by X-ray diffraction, atomic force microscopy, and electron probe micro analyzer. We find that the substrate temperature is a critical factor in determining the phase of the NbNx films. For a substrate temperature up to 450 degrees C the film showed poor crystalline quality. With temperature increase the film became textured and for a substrate temperature of 650-850 degrees C, mix of cubic delta-NbN and hexagonal phases (beta-Nb2N + delta'-NbN) were formed. Films with a mainly beta-Nb2N hexagonal phase were obtained at deposition temperature above 850 degrees C. The c/a ratio of beta-Nb2N hexagonal shows an increase with increased nitrogen content. The surface roughness of the NbNx films increased as the temperature was raised from 450 to 850 degrees C. (C) 2011 Elsevier B.V. All rights reserved.U.S. DOEUnited States Department of Energy (DOE) [DE-AC05-06OR23177, DE-FG02-97ER45625]; National Science FoundationNational Science Foundation (NSF) [DMR-9988669, MRI-0821180]We would like to thank S. Herman for his great support during the EPMA measurements, Dr. G. Ciovati for providing the niobium samples, and Dr. R. Pike for giving us access to XRD. This work was partially supported by U.S. DOE Contract Nos. DE-AC05-06OR23177 and DE-FG02-97ER45625 and by the National Science Foundation Grant Nos. DMR-9988669 and MRI-0821180