Morphological and Structural Properties of NbN Thin Films Deposited by Pulsed Laser Deposition

Abstract

Niobium nitride (NbN) films were deposited on Nb using pulsed laser deposition (PLD), and the effect of substrate deposition temperature on the preferred orientation, phase, and surface properties of NbN films were explored by x-ray diffraction (XRD) and atomic force microscopy (AFM). It was found that the substrate deposition temperature has a significant influence on properties of the NbN films, leading to a pronounced change in the preferred orientation of the crystal structure and the phase. We find that substrate temperature is a critical factor in determining the phase of the NbN films. For a substrate temperature of 650 °C 850 °C, the NbN film formed in the cubic δ-NbN phase mixed with the β-Nb2N hexagonal phase. With an increase in substrate temperature, NbN layers became β-Nb2N single phase. Essentially, films with a mainly β-Nb2N hexagonal phase were obtained at deposition temperatures above 850 °C. Surface roughness and crystallite sizes of the β-Nb2N hexagonal phase increased as the deposition temperatures increased.