Zirconium nitrides deposited by dual ion beam sputtering: physical properties and growth modelling

Zirconium nitrides reveal interesting optical and electrical properties whi ch highly depend on the nitrogen stoichiometry. Indeed, the material exhibi ts a transition from the stable metallic ZrN (optical index for bulk at 633 nm: N = 0.5 - i3.2) to the metastable semi-transparent insulating Zr3N4 (N = 3.2 - i0.4). This work deals with the elaboration of homogeneous ZrN-lik e and Zr3N4-like coatings. These have been prepared using reactive Dual Ion Beam Sputtering (DIBS) using a Zr target and N-2 or N-2 + Ar reactive gas. The influence of different elaboration parameters lion energy, gas composi tion of the reactive beam and substrate temperature) on the nitrides compos ition and on their optical and electrical properties was particularly studi ed. A model was proposed to explain the influence of energy and temperature on the nitrogen composition. The nitrogen stoichiometry was shown to be co ntrolled by a competitive mechanism between implantation of excess nitrogen amount in the subsurface and their elimination by exodiffusion. Tl-le firs t phenomenon is mainly controlled by the ion energy whereas the second one is enhanced by a high temperature and a high irradiation defects density. T herefore, the Zr3N4-like nitrides were obtained with low temperature and hi gh energy (200 eV) conditions whereas high temperature and low energy led t o ZrN-like materials. (C) 1999 Elsevier Science B.V. All rights reserved.