Near-infrared absorption in transparent conducting oxides (TCOs) is usually caused by electronic intraband transition at high doping levels. Improved infrared transparency is commonly explained by enhanced drift mobility in these TCOs. Here, an alternative cause behind the high infrared transparency of La-doped barium stannate (LBSO) transparent electrodes is presented. Following the Drude model formalism, we reconstructed spectrally resolved dielectric permittivity for a set of thin films with different free electron concentrations. A comparison of optical properties of LBSO with the tin-doped indium oxide thin films with identical carrier concentrations suggests that the redshift of the screened plasma wavelength for LBSO originates from its large high-frequency dielectric constant of 4.4, one of the highest reported for the s-orbital-based TCOs. Moreover, our measurements confirm an optical mobility significantly higher (>300 cm2/V s) than the drift mobility, effectively suppressing the free carrier absorption. These factors enable high infrared transparency of LBSO films and motivate further exploration of LBSO as broadband TCOs for solar cells and nanophotonics.

中文翻译：

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高导电钙钛矿锡酸盐 BaSnO3 红外透明度的起源

透明导电氧化物 (TCO) 中的近红外吸收通常是由高掺杂水平的电子带内跃迁引起的。这些 TCO 中漂移迁移率的提高通常可以解释红外透明度的提高。在这里，介绍了 La 掺杂的锡酸钡 (LBSO) 透明电极的高红外透明度背后的另一个原因。遵循 Drude 模型形式，我们重建了一组具有不同自由电子浓度的薄膜的光谱分辨介电常数。LBSO 与具有相同载流子浓度的掺锡氧化铟薄膜的光学特性的比较表明，LBSO 的屏蔽等离子体波长的红移源于其 4.4 的大高频介电常数，这是报道的最高值之​​一。基于 s 轨道的 TCO。此外，我们的测量证实光迁移率明显高于漂移迁移率 (>300 cm2/V s)，有效抑制了自由载流子吸收。这些因素使 LBSO 薄膜具有高红外透明度，并促使进一步探索 LBSO 作为太阳能电池和纳米光子学的宽带 TCO。