Flexible multifunctional hard coatings based on chromium oxynitride for pressure-sensing applications

Abstract

The present work reports on the development of piezoresistive chromium oxynitride (CrN1−xOx) thin films deposited on flexible polymeric substrates. The relationship between the reactive gas supply (composed of 15% O2 and 85% N2) and the electromechanical response was analyzed in CrN1−xOx thin films, produced by glancing angle deposition (GLAD) in a sputtering DC-reactive environment. GLAD was used to modify the normal columnar growth microstructure into an inclined (zigzaglike) architecture, allowing us to the tune of the mechanical and electrical responses of the films. The piezoresistive response was quantified by the gauge factor (GF), reaching values from 2.3±0.1 up to 32.4±0.4 as the reactive gas was increased. The highest values of the GF of the CrN1−xOx films were found in the samples with hardness values in the order of 15.5 GPa and elastic modulus close to 173 GPa. This work shows that the change of characteristics, such as microstructure and the zigzag architecture of the films, can be powerful tools to improve the sensibility by the GF of the CrN1−xOx films and turn Cr-based thin films into an interesting multifunctional system with protective and sensing capabilities.