Telecom wavelength single-photon emitters in β-Ga₂O₃

Solid-state defects, essentially artificial atoms trapped in solids, in wide band-gap semiconductors exhibit promising characteristics for applications in quantum computing, communication, and sensing. In this study, we report first principles calculations of transition metal impurities, such as chromium (Cr), manganese (Mn), iron (Fe), and cobalt (Co), at gallium (Ga) sites during the synthesis of β-Ga₂O₃. These impurities are found to be more stable when they form clusters in octahedral and tetrahedral positions within the Ga lattice. Thermodynamic charge transition level analysis suggests these impurities act as deep acceptors and donors within the band gap of β-Ga₂O₃. Notably, these transition metal clusters provide a two-level system within the band gap in the +1 charge state, making them suitable single-photon emission sources. The zero-phonon lines of these charged clusters are situated around 1 eV, a proximity to the telecom band, enabling their operation at telecom wavelengths for low-loss fiber transmission. Our findings propose that transition-metal clusters in β-Ga₂O₃ holds promise for quantum information science.