Oxygen diffusion barriers for epitaxial thin-film heterostructures with highly conducting SrMoO3 electrodes
Oxygen diffusion barriers for epitaxial thin-film heterostructures with highly conducting SrMoO3 electrodes
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DOI：
10.1063/1.5129767
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发表时间：
2020-02
影响因子：
3.2
通讯作者：
P. Salg;L. Zeinar;A. Radetinac;D. Walk;H. Maune;R. Jakoby;L. Alff;P. Komissinskiy
中科院分区：
文献类型：
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作者：
P. Salg;L. Zeinar;A. Radetinac;D. Walk;H. Maune;R. Jakoby;L. Alff;P. Komissinskiy
具有Mo 4 + 4d 2 电子构型的过渡金属钙钛矿氧化物SrMoO 3 在单晶形式下表现出5.1 μ Ω cm的室温电阻率，因此被认为是全氧化物微电子器件的重要导电电极材料。 SrMoO 3 薄膜中不利的 Mo 4 + 价态的稳定需要还原生长条件，这些条件通常与生长具有完全氧化功能层的外延异质结构（例如，可调谐电介质 Ba xSr 1 − xTiO 3 ）所需的高氧化环境不相容。有趣的是，钙钛矿钛酸盐覆盖层SrTiO 3 、BaTiO 3 和Ba 0.5Sr 0.5TiO 3 中只有少数晶胞充当有效的氧屏障，并在较宽的薄膜生长参数范围内最大限度地减少SrMoO 3 氧化成电绝缘的SrMoO 4 。通过 X 射线光电子能谱测定 SrMoO 3 中的 Mo 价态，用于分析通过覆盖层的氧扩散。在 Ba 0.5Sr 0.5TiO 3 中观察到最低水平的氧扩散。厚度仅为 6 个晶胞的 Ba 0.5Sr 0.5TiO 3 薄膜在 630 °C 的温度下在氧分压高达 8 mTorr 的情况下保留了 SrMoO 3 底层中的 Mo 4 + 氧化态。因此，结果表明，覆盖有原子级薄Ba 0.5Sr 0.5TiO 3 的SrMoO 3 薄膜在氧气环境中仍保持导电性，并且可以与其他功能材料集成到全氧化物薄膜异质结构中。具有Mo 4 + 4d 2 电子构型的过渡金属钙钛矿氧化物SrMoO 3 在单晶形式下表现出5.1 μ Ω cm的室温电阻率，因此被认为是用于全氧化物微电子器件的杰出导电电极材料。 SrMoO 3 薄膜中不利的 Mo 4 + 价态的稳定需要还原生长条件，这些条件通常与生长具有完全氧化功能层的外延异质结构（例如，可调谐电介质 Ba xSr 1 − xTiO 3 ）所需的高氧化环境不相容。有趣的是，钙钛矿钛酸盐覆盖层SrTiO 3 、BaTiO 3 和Ba 0.5Sr 0.5TiO 3 中只有少数晶胞充当有效的氧屏障，并在较宽的薄膜生长参数范围内最大限度地减少SrMoO 3 氧化成电绝缘的SrMoO 4 。通过 X 射线光电子能谱测定 SrMoO 3 中的 Mo 价态，用于分析...
Transition metal perovskite oxide SrMoO 3 with a Mo 4 + 4d 2 electronic configuration exhibits a room-temperature resistivity of 5.1 μ Ω cm in a single-crystal form and, therefore, is considered a prominent conducting electrode material for all-oxide microelectronic devices. Stabilization of the unfavorable Mo 4 + valence state in SrMoO 3 thin films necessitates reductive growth conditions that are often incompatible with a highly oxidative environment necessary to grow epitaxial heterostructures with fully oxygenated functional layers (e.g., tunable dielectric Ba xSr 1 − xTiO 3). Interestingly, only a few unit cells of the perovskite titanate capping layers SrTiO 3, BaTiO 3, and Ba 0.5Sr 0.5TiO 3 act as an efficient oxygen barrier and minimize SrMoO 3 oxidation into electrically insulating SrMoO 4 in the broad range of the thin-film growth parameters. The Mo valence state in SrMoO 3, determined by x-ray photoelectron spectroscopy, is used to analyze oxygen diffusion through the capping layers. The lowest level of oxygen diffusion is observed in Ba 0.5Sr 0.5TiO 3. A Ba 0.5Sr 0.5TiO 3 film with a thickness of only 6 unit cells preserves the Mo 4 + oxidation state in the SrMoO 3 underlayer up to the oxygen partial pressure of 8 mTorr at the temperature of 630 °C. Results, therefore, indicate that SrMoO 3 films covered with atomically thin Ba 0.5Sr 0.5TiO 3 remain conducting in an oxygen environment and can be integrated into all-oxide thin-film heterostructures with other functional materials.Transition metal perovskite oxide SrMoO 3 with a Mo 4 + 4d 2 electronic configuration exhibits a room-temperature resistivity of 5.1 μ Ω cm in a single-crystal form and, therefore, is considered a prominent conducting electrode material for all-oxide microelectronic devices. Stabilization of the unfavorable Mo 4 + valence state in SrMoO 3 thin films necessitates reductive growth conditions that are often incompatible with a highly oxidative environment necessary to grow epitaxial heterostructures with fully oxygenated functional layers (e.g., tunable dielectric Ba xSr 1 − xTiO 3). Interestingly, only a few unit cells of the perovskite titanate capping layers SrTiO 3, BaTiO 3, and Ba 0.5Sr 0.5TiO 3 act as an efficient oxygen barrier and minimize SrMoO 3 oxidation into electrically insulating SrMoO 4 in the broad range of the thin-film growth parameters. The Mo valence state in SrMoO 3, determined by x-ray photoelectron spectroscopy, is used to analyze ...