Multiple strong impacts of anion doping Λ (Λ = oxygen vacancy, nitrogen, or hydrogen) on the optical properties in the near-infrared to vacuum ultraviolet spectral range are experimentally revealed in cube-on-cube-type epitaxial perovskite BaTiO3−δΛδ films (δ ≤ 0.01) grown on (001)SrTiO3 substrates. Compared to the reference undoped films and bulk crystal, the anion-doped films exhibit massive changes of the index of refraction in the transparency range Δn of ∼0.1 to 0.2, a profound bandgap widening ΔEg of ∼0.3 eV to 0.4 eV, a dopant-specific near-edge absorption, and doping-induced interband transitions. Both the conduction-band uplift and the changes in the index of refraction are ascribed to the internal stress and electric field, which result from epitaxially controlled dopant locations in the [Ba–O](001) planes. The dopant-induced in-gap states are responsible for the near-edge absorption, whereas the dopant-induced conduction-band states are suggested to modify the interband transitions and the intrinsic elasto- and electro-optic coefficients.

中文翻译：

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外延钛酸钡薄膜中阴离子掺杂的多重光学影响

在立方体上立方型外延钙钛矿 BaTiO3−δΛδ 薄膜中，实验揭示了阴离子掺杂 Λ（Λ = 氧空位、氮或氢）对近红外到真空紫外光谱范围内的光学特性的多重强烈影响。 δ ≤ 0.01) 在 (001) SrTiO3 衬底上生长。与参考未掺杂薄膜和块状晶体相比，阴离子掺杂薄膜在透明度范围 Δn Δn 约 0.1 至 0.2 内表现出巨大的折射率变化，带隙加宽 ΔEg 约 0.3 eV 至 0.4 eV，掺杂剂-特定的近边吸收和掺杂引起的带间跃迁。导带隆起和折射率的变化都归因于内应力和电场，这是由 [Ba-O](001) 平面中外延控制的掺杂位置引起的。