Dark Current Suppression and Enhancement of Photoconductivity Using Annealing and Sn-Ion Implantation in β-Ga₂O₃ Based UV Photodetector

β-Ga₂O₃-based self-powered solar-blind deep ultraviolet (DUV) photodetectors (PDs) are well known for their suitability for various optoelectronic applications. While Sn doping has been previously used to modify the electrical properties of β-Ga₂O₃, the impact of Sn implantation and subsequent annealing on PD performance remains unexplored. This study investigates the effects of Sn implantation and annealing on Ga₂O₃-based DUV PDs, aiming to optimize their sensitivity, response time, and self-powered operation. In this work, we report a systematic investigation of the effect of Sn ion implantation under different conditions such as energy, charge, and dosage, as well as post-annealing of the pulsed laser deposition grown β-Ga₂O₃ films on their electrical, structural, and optical properties. We also study the correlation between implantation and annealing with the performance of DUV PD devices. X-ray diffraction (XRD) studies reveal that the orientation of the films along the (-201) plane largely remains unaffected due to implantation, although there is a slight improvement in crystal quality post-annealing. Raman studies indicate the formation of vacancies in octahedral Ga₂O₃ chains due to substituting Sn ions at Ga sites, which could play a crucial role in enhancing the optical and electrical properties. XRD and Raman studies on all films confirm good damage recovery due to annealing after implantation. High-resolution transmission electron microscopy (HR-TEM) along with secondary ion mass spectroscopy (SIMS) reveal that the implantation depth is approximately 160 nm from the surface and the implanted region consists of smaller crystallites, while RBS studies are consistent with XRD and Raman, confirming the damage recovery post-annealing. UV-Vis spectroscopy shows a reduction in the bandgap as the implantation dosage increases due to the introduction of donor states below the conduction band. PD devices based on as-grown β-Ga₂O₃ exhibit significant dark current attributed to persistent photoconductivity (PPC), whereas the PDs based on annealed and Sn-implanted β-Ga₂O₃ films exhibit almost no dark current. Implanted Ga₂O₃ PDs demonstrate a remarkable reduction in dark current by 10⁷ times and an improvement in the photo-to-dark current ratio by 10⁵ times compared to as-grown PDs, along with an improvement in the rise and fall time. The effect of double charge on the ions, implantation energy, and dosage on device performance is studied to understand the underlying mechanism of dark current suppression. We discuss the mechanism of persistent photoconductivity suppression and its connection to surface oxygen vacancies, as well as the effect of annealing using X-ray photoelectron spectroscopy (XPS). This is the first report on a study of significantly enhanced self-powered solar-blind DUV PD devices fabricated via Sn⁺ ion implantation (post-annealed) β-Ga₂O₃.