Characterization and Optical Properties of Erbium doped As2S3 Films Prepared by Multi-layer Magnetron Sputtering

TL;DR

This paper reports on the fabrication and characterization of erbium-doped As2S3 films prepared by multi-layer magnetron sputtering, demonstrating their optical properties, chemical composition, and potential for integrated photonic devices.

Contribution

It introduces a novel sputtering method for producing high-quality Er:As2S3 films with controlled stoichiometry and demonstrates their application in integrated Mach-Zehnder interferometers.

Findings

Refractive index and absorption coefficient match sputtered As2S3.

No detectable Er-S clusters or photo-induced As2O3.

Active erbium ions emit green luminescence under laser pumping.

Abstract

As2S3 film doped with erbium is prepared using multi-layer magnetron sputtering. The optical properties were measured by reflectance spectroscopy, and its chemical composition is examined by x-ray photoelectron, Rutherford backscattering, and Raman spectroscopy. The results show that the refractive index and absorption coefficient follow closely to a sputtered As2S3 film, and there are no detectable Er-S clusters and photo-induced As2O3 in the film. Rutherford backscattering spectroscopy shows that the film is homogeneous, and revealed the concentration level of erbium, and the stoichiometry of the film. The deposition method was used to fabricate an integrated Erdoped As2S3 Mach-Zehnder Interferometer and the presence of active erbium ions in the waveguide is evident from the green luminescence it emitted when it was pumped by 1488 nm diode laser. This method is attractive because the doping process can produce an Er:As2S3 film that is close to the ideal stoichiometry of As2S3 with lower risk of photo-decomposed As2O3 crystals developing on the surface when the as-deposited film is exposed to the environment.