Electrical, optical and mechanical properties of sputtered CrNy and Cr1-xSixN1.02 thin films

We have investigated the electrical, optical and mechanical properties of CrNy and Cr1-xSixN1.02 films as a function of N and Si contents near the fcc-CrN stoichiometric composition. Polycrystalline CrNy with 0.93<y<1.15 and Cr1-xSixN1.02 with 0<x<0.16 were deposited by reactive magnetron sputtering. Optical reflectivity and electrical resistivity measurements indicate that the electronic properties of CrNy and Cr1-xSixN1.02 thin films are strongly dependent on their chemical composition. The main changes in the optical properties of CrNy and Cr1-xSixN1.02 films as a function of N or Si content mainly occur below 1.5 eV, Substoichiometric CrNy films with 0.93<y<0.98 exhibit room temperature resistivity rho(RT) values of (1.2-7) x 10(-3) Omega cm, metallic behavior and an antiferromagnetic orthorhombic phase transition at approximately 260 K. In contrast, overstoichiometric CrNy (1.05<y<1.15) and Cr1-xSxN1.02 films exhibit rho(RT) values of (1.2-4) x 10(-2) Omega cm and negative temperature coefficients of resistivity. Finally, the hardness values of CrNy films depend little on the chemical composition but are influenced by the film morphology: the nanohardness values of (1 1 1) CrNy are typically 12-14 GPa while (0 0 2) CrNy exhibit nanohardness values of 18 GPa. The addition of small amounts of Si increases the hardness values up to 22 GPa for Cr0.94Si0.06N1.02. (C) 2003 Elsevier B.V. All rights reserved.