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

Abstract 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 (Ga 2 O 3 ) 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 Ga 2 O 3 in ultraviolet detection. Here, the trivalent lanthanide elements are used as the homovalent substitution of gallium in Ga 2 O 3 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 Ga 2 O 3 , resulting in a significant shift of the conduction band. Furthermore, an ITO/Ga 2 O 3 :Ln/Au structure photodetector is prepared by Ga 2 O 3 :Lu thin films, which exhibits an ultra‐low dark current (−2.09 × 10 − ¹ 3 A) and a fast response speed (321/136.8 ms), demonstrating the great prospect of Ga 2 O 3 :Ln semiconductors in photoelectronics.