Layered cobalt oxides based on the hexagonal CoO₂ layer, e.g., Na_xCoO₂ and [CoCa₃O₃]_0.62CoO₂ (or “Ca₃Co₄O₉”), are promising thermoelectric materials. Here, the authors investigate the atomic layer deposition (ALD) of these materials in a thin-film form; this is not trivial, in particular, for the former compound, as both Na and Co are little challenged as components of ALD thin films. The authors employ diketonate precursors for all the metal constituents and ozone as the source of oxygen. In both cases, a postdeposition heat-treatment in O₂ is applied to get crystalline coatings; the processes are found amazingly robust in terms of metal precursor pulsing ratios. A striking difference between the two processes is the resultant morphology: while the Ca₃Co₄O₉ films grow highly homogeneous and smooth, the Na_xCoO₂ coatings exhibit a rather unique reproducible 10–20 μm scale channel-like island structure for all x values investigated. Finally, the authors characterized their ALD Ca₃Co₄O₉ films for their chemical, structural, and physical property details not previously reported.

中文翻译：

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热电层状钴氧化物的原子层沉积

基于六角形CoO ₂层的层状氧化钴，例如Na _x CoO ₂和[CoCa ₃ O ₃ ] _0.62 CoO ₂（或“ Ca ₃ Co ₄ O ₉ ”），是有前途的热电材料。在这里，作者研究了这些材料以薄膜形式的原子层沉积（ALD）。尤其对于前一种化合物而言，这并不是微不足道的，因为Na和Co都很少受到ALD薄膜成分的挑战。作者将二酮酸酯前体用于所有金属成分，并将臭氧用作氧的来源。在这两种情况下，在O _2中进行沉积后热处理用于获得结晶涂层；就金属前驱体的脉冲比而言，发现该过程具有惊人的鲁棒性。这两个过程之间的显着区别是所得到的形态：当钙₃共₄ ø ₉膜生长高度均匀和光滑，所述的Na _X CoO的_2种涂层表现出相当独特的可再现的10-20  μ为米尺度通道状岛结构研究所有x值。最后，作者对ALD Ca ₃ Co ₄ O ₉薄膜的化学，结构和物理特性进行了详细描述，而以前没有报道过。