Defect passivation and enhanced UV emission in β-Ga2O3 via remote fluorine plasma treatment

This study investigates the incorporation of fluorene (F) donors in β-Ga2O3 and its effects on luminescence, defect structure and carrier dynamics. Monoclinic β-Ga2O3 nanowires (NWs) are synthesized via chemical vapour deposition and subsequently doped with F using remote SF6 plasma treatment, leveraging their nanoscale cross sections. Photoelectron spectroscopy reveals F incorporation at oxygen sites and the formation of strong Ga–F bonds without sulfur contamination, while the monoclinic crystal structure remains intact. The impact of F doping is assessed using hyperspectral cathodoluminescence (CL) mapping and time-resolved spectroscopy of individual NWs. The β-Ga2O3 NWs exhibit a strong characteristic UV peak at 3.40 eV, associated with self-trapped holes, and visible defect-related emissions. After F incorporation, an additional UV emission at 3.64 eV emerges, attributed to shallow F donor-deep acceptor pair recombination, while the defect-related emissions are strongly supressed as F atoms occupy oxygen vacancies. Carrier lifetime increases from 9.2 ns to 17.0 ns with increasing F concentration along the nanowire. The work highlights the utility of F plasma processing to passivate intrinsic defects in Ga2O3 and the influence of F donors on the UV emission of β-Ga2O3.