Lanthanide-Doped Ga2O3: A Route to Bandgap Engineering for Ultraviolet Detection

The demand for next-generation wide bandgap semiconductors is driven by applications such as solar-blind ultraviolet detection and ultra-high power electronics, and gallium oxide (Ga₂O₃) has emerged as a highly promising candidate material due to its ultra-wide bandgap, high intrinsic breakdown field strength, and quite significant ultraviolet absorption. However, the lack of doping engineering based on substituting isovalent elements to achieve bandgap tuning has limited the development of Ga₂O₃ in ultraviolet detection. Here, the trivalent lanthanide elements are used as the homovalent substitution of gallium in Ga₂O₃ to achieve effective regulation of the optical bandgap. The theoretical calculation shows that the doped lanthanide (Lu) introduces its 6s orbital electrons to the conduction band of Ga₂O₃, resulting in a significant shift of the conduction band. Furthermore, an ITO/Ga₂O₃:Ln/Au structure photodetector is prepared by Ga₂O₃:Lu thin films, which exhibits an ultra-low dark current (−2.09 × 10⁻¹³ A) and a fast response speed (321/136.8 ms), demonstrating the great prospect of Ga₂O₃:Ln semiconductors in photoelectronics.