Atomic layer deposition of ternary oxides of platinum group elements

含贵金属的多种氧化物(除铜外)的原子层沉积(ALD)研究很少，尽管对于铂族元素金属及其许多简单氧化物的ALD工艺已经得到了很好的发展。然而，复合氧化物具有非常重要的技术性质，因此研究这些氧化物薄层的沉积过程及其表征是非常有意义的。三元贵金属氧化物的族包括，除其他外，氟碳磷矿和焦绿石虹酸盐的晶群。尤其是磷锌矿PdCoO2、PdCrO2和PtCoO2，由于它们以单晶的形式具有很高的导电性，近年来受到了一些关注。这是由于二维贵金属层内电子的高迁移率，这也使这些材料成为观察流体动力学电子流的候选材料。计算表明，PtCoO2是一种很有前途的自旋电子应用材料。此外，最近的研究表明，这三种材料都是酸性电解液中析氢反应的优良电催化剂，在某些条件下甚至超过了铂。近年来，由于电子关联和自旋-轨道耦合的结合，导致金属-半导体跃迁和非共线反铁磁性等效应的存在，热氯Ir酸盐受到了越来越多的关注。这里还值得一提的是，Y2Ir2O7在一定温度范围内应该表现出Weyl半金属的性质的预测。Weyl半金属是目前拓扑材料领域中研究较多的一类材料。该科学项目追求的目标是使用ALD从气相中沉积和表征薄层三元氧化物，其中一种金属属于铂族。重点放在两个晶群上，即黑云母(PdCoO2、PdCrO2和PtCoO2)和焦绿石虹酸盐(Y2Ir2O7)。首先为各种材料沉积非晶层。在此基础上，通过快速热处理获得结晶层。然后分析这些层的元素组成和晶体结构。最后，详细研究了薄膜的物理性质，如随温度变化的电导率和获得理想晶相的薄膜的磁有序。目的是确定工艺条件和这些物理性能之间的关系。

Atomic layer deposition (ALD) of multiple oxides containing noble metals (apart from Cu) has been little studied, although ALD processes are well developed for the platinum group elemental metals and many of their simple oxides. However, the multiple oxides have technologically very important properties, so that investigations into deposition processes for thin layers of these oxides and their characterizations are of great interest. The group of ternary noble metal oxides includes, among other things, the crystal groups of delafossite and pyrochlore iridate. In particular, the delafossites PdCoO2, PdCrO2, and PtCoO2 have received some attention in recent years because of their high conductivity in the form of single crystals. This is due to the high mobility of the electrons within the two-dimensional noble metal-containing layers, which also makes these materials candidates for the observation of hydrodynamic electron flow. Calculations have shown that PtCoO2 is a promising material for spintronic applications. Furthermore, it has recently been demonstrated that all three materials are excellent electrocatalysts for the hydrogen evolution reaction in acidic electrolytes, even surpassing platinum under certain conditions. Pyrochlorine iridates have received increased interest in recent years because of the combination of electron correlation and spin-orbit coupling leading to effects such as metal–semiconductor transitions and non-collinear antiferromagnetism. It is also worth mentioning here the prediction that Y2Ir2O7 should exhibit the properties of a Weyl semimetal in a certain temperature range. Weyl semimetals are currently an intensively studied material class in the field of topological materials. The scientific project pursues the goal of depositing and characterizing thin layers of ternary oxides, in which one of the metals belongs to the platinum group, from the gas phase using ALD. The focus is on two crystal groups, the delafossites (PdCoO2, PdCrO2 and PtCoO2) and the pyrochlore iridates (Y2Ir2O7). Amorphous layers are first deposited for the various materials. From these, crystalline layers are obtained by means of rapid thermal processing. The layers are then analyzed for their elemental composition and crystal structure. Finally, the physical properties such as the temperature-dependent electrical conductivity and the magnetic ordering of films for which the desired crystalline phase has been achieved are studied in detail. The aim is to determine the relationships between the process conditions and these physical properties.