Structural and Optical Characteristics of beta-Ga2O3 Implanted with Rare Earth Ions

TL;DR

This study explores how rare-earth ion implantation affects the structural and optical properties of beta-Ga2O3 crystals, revealing defect behaviors, emission mechanisms, and the impact of annealing on material performance.

Contribution

It provides new insights into defect evolution and excitation mechanisms of RE3+ ions in beta-Ga2O3, aiding optimization of optical properties in these materials.

Findings

Implantation-induced disorder is largely insensitive to RE species.

RE ion introduction adds emission lines from RE3+ electronic transitions.

RE-related emission remains efficient despite lattice disorder.

Abstract

We investigated the structural evolution and optical properties of beta-Ga2O3 crystals implanted with different rare-earth (RE) ions using channeling Rutherford Backscattering Spectrometry, Positron Annihilation, Photoluminescence, and Photoluminescence Excitation spectroscopies. The studies reveal that implantation-induced disorder, accompanying phase transitions, and post-annealing structural recovery are largely insensitive to the implanted RE species. The defect microstructure is also found to be similar for all implanted RE ions. Thermal annealing does not completely remove radiation-induced defects but instead drives their rearrangement into larger defect complexes. Unimplanted (virgin) beta-Ga2O3 exhibits strong UV-visible emission attributed to oxygen vacancies, whereas the introduction of RE ions produces additional emission lines originating from electronic transitions within RE3+ ions. The results indicate that RE3+ ions are excited through the host conduction band, followed by non-radiative relaxation to the 4f excited states and radiative decay to the respective ground states. Fluence-dependent studies of Yb3+ reveal the onset of concentration quenching, while RE-related emission remains efficient even in the presence of substantial lattice disorder. These findings provide new insight into defect evolution in ion-implanted beta-Ga2O3 and clarify the excitation mechanisms of RE3+ ions, offering guidance for optimizing the optical performance of beta-Ga2O3:RE materials.