Formation of Si–Er–O structures in Si by Ar-irradiation for harvesting light at the 4f intraband transition

Abstract

In the pursuit of developing cost-effective optically active media for silicon-based infrared emitters, we employed a multi-step fabrication process to create silicon films doped with erbium (Er) and oxygen (O). The process involved physical vapor deposition (PVD) followed by ion beam surface modification (IBM) and oxygen incorporation that are facilitated by Ar⁺ and O²⁺ implantation, and thermal annealing techniques. The resulting silicon films, denoted as Si–Er–O, demonstrated efficient room-temperature emission, indicative of 4f transitions. Notably, the observed photoluminescence (PL) manifests Stark-split ⁴I_13/2 - ⁴I_15/2 transitions characteristic of Er³⁺ impurity centers mimicking that of Er in optical fiber materials. The concentration distributions of the dopants within the films were determined utilizing Rutherford backscattering spectrometry (RBS). The main finding of this study is the correlation between Er concentration, oxygen presence, and optical activity in Si–Er–O films. Results demonstrate that the optical activity of Er³⁺ ions rise with the O/Er atomic concentration ratio, peaking at a specific ratio; corroborating earlier results from other researchers in the literature. Elevated Er concentration correlates with decreased PL signals, confirming that Er–O association enhances optically active Er³⁺, while Er–Er association inhibits it. This optimal balance suggests potential improvements in light emitting diodes (LED) manufacturing via PVD. More importantly, the efficacy of IBM is evident in its role in enhancing Er thermal diffusion and achieving optimal optical activation. Furthermore, the study highlights the importance of controlling processing conditions to achieve desired composition and properties, with implications for enhancing LED efficiency, especially in the infrared spectral range.