Optical properties of Y2O3 thin films doped with spatially controlled Er3+ by atomic layer deposition

We report in this work the optical properties of Er3+-doped Y2O3, deposited by radical enhanced atomic layer deposition. Specifically, the 1.53 µm absorption cross section of Er3+ in Y2O3 was measured by cavity ring-down spectroscopy to be (1.9±0.5)×10-20 cm2, about two times that for Er3+ in SiO2. This is consistent with the larger Er3+ effective absorption cross section at 488 nm, determined based on the 1.53 µm photoluminescence yield as a function of the pump power. X-ray photoelectron spectroscopy and Rutherford backscattering spectroscopy were used to determine the film composition, which in turn was used to analyze the extended x-ray absorption fine structure data, showing that Er was locally coordinated to only O in the first shell and its second shell was a mixture of Y and Er. These results demonstrated that the optical properties of Er3+-doped Y2O3 are enhanced, likely due to the fully oxygen coordinated, spatially controlled, and uniformly distributed Er3+ dopants in the host. These findings are likely universal in rare-earth doped oxide materials, making it possible to design materials with improved optical properties for their use in optoelectronic devices.