An optoelectronic device including a substrate, a half-boat-shaped material layer, a deep trench isolation structure, and an optical waveguide is provided. The substrate has a first area. The half-boat-shaped material layer is disposed in the substrate within the first area. The refractive index of the half-boat-shaped material layer is lower than that of the substrate. A top surface of the half-boat-shaped material layer is coplanar with the surface of the substrate. The deep trench isolation structure is disposed in the substrate within the first area and located at one side of a bow portion of the half-boat-shaped material layer. The optical waveguide is disposed on the substrate within the first area. The optical waveguide overlaps a portion of the deep trench isolation structure and at least a portion of the half-boat-shaped material layer.