Optical and Mechanical Properties of Europium-Doped Silicon Nitride Thin Films Deposited by ECR-PECVD with Magnetron Sputtering

Abstract Optical and mechanical properties of europium (Eu)-doped silicon nitride (SixNy) films were investigated as a function of the sputtering power applied to the Eu metal target and argon flow into the deposition chamber. Films were fabricated by an electron cyclotron resonance plasma-enhanced chemical vapor deposition (ECR-PECVD) system combined with magnetron sputtering for in-situ rare-earth doping. Results show that Eu-doped SixNy films fabricated with higher sputtering power exhibit intense red emission when annealed above 1000°C, making the luminescence visible under daylight conditions. Variable-angle spectroscopic ellipsometry analysis shows that the refractive index and film thickness are strongly dependent on the sputtering power; however, argon (Ar) flow has minimal influence. High-resolution X-ray diffraction reveals that the crystalline phases in the films play a crucial role in efficient Eu emission. Additionally, the films show increased hardness, up to 18 GPa, and an elastic modulus of 160 GPa, ensuring their durability and performance as cladding layers in photonic devices. These mechanical properties are essential for maintaining structural integrity and preventing defects, which are critical for the reliability of optoelectronic devices. The combination of strong emissions and good mechanical properties make Eu-doped SixNy films suitable for optoelectronic and solar cell applications, where both efficient light emission and material stability are essential.