Functionalization of Cuprous Oxide: From Doped Binary to Cu-based Ternary Oxide Films

目前的建议是对先前的DFG项目的后续，该项目旨在用表面科学方法制备和表征氧化亚铜薄膜。这个过期的项目成功地澄清了与Cu2O有关的一些基本问题，Cu2O是一种具有巨大科学和技术相关性的材料。主要的进展是：(1)在确定的反应条件下对cu氧化的动力学和热力学进行了研究。为此，开发了一种新的光学技术，用于原位监测氧化前沿，并用于建立Cu-O相图作为压力和温度的函数（ii）在Au(111), Pt（111）和Mo（001）上生长的Cu-O单层膜的性质。实验揭示了在真空环境中不可能生长厚的Cu-氧化物膜（iii）通过高压氧化方案生长大块型Cu2O膜的配方（iv）与所有现有文献模型相比，Cu2O（111）表面总是重建且不包含低配位Cu离子或O空位的结构阐明。体型Cu2O（111）的新制备方案的可用性为在后续项目中处理这种迷人材料的其他特性提供了坚实的基础，其中包括以下关键方面：(i)表征主导材料电子（p型电导）和化学性质的晶格缺陷（ii）空间分辨探测激子，作为Cu2O的基本光学模式；以及它们与晶格缺陷的相互作用（iii）通过掺杂释放Cu2O中带隙复合的偶极禁止性质，并随后在具有有利光学跃迁宇称的带边缘插入缺陷态（iv）将掺杂方案扩展到具有新型光学和化学性质的三元cu基氧化物，例如CuAlO2和Cu2V2O7，用于光催化水的分裂。所有实验都是在特高压环境中使用最先进的表面科学技术进行的，特别是在原子水平上使用扫描隧道和光学近场显微镜，并将伴随着高水平的DFT计算。

The present proposal is a follow-up to previous DFG project that aimed at the preparation and characterization of cuprous oxide films with surface science methods. The expired project successfully clarified a number of fundamental questions in connection with Cu2O, a material of enormous scientific and technological relevance. The main advances concern: (i) the kinetics and thermodynamics of Cu-oxidation as probed at defined reaction conditions. For this purpose, a new optical technique was developed for the in-situ monitoring of oxidation fronts and used to establish a Cu-O phase diagram as a function of pressure and temperature(ii) the nature of Cu-O monolayer films grown on Au(111), Pt(111) and Mo(001). The experiments revealed the impossibility to grow thick Cu-oxide films in a vacuum environment(iii) a recipe to grow bulk-type Cu2O films via a high-pressure oxidation scheme(iv) the structural elucidation of the Cu2O(111) surface that always reconstructs and comprises neither low-coordinated Cu ions nor O vacancies, in contrast to all existing literature models.The availability of a new preparation scheme for bulk-type Cu2O(111) represents a firm basis to address other properties of this fascinating material during a follow-up project with these key aspects: (i) Characterization of lattice defects that dominate the electronic (p-type conductance) and chemical properties of the material(ii) Spatially resolved detection of excitons, as the fundamental optical mode of Cu2O, and their interplay with lattice imperfections(iii) Release of the dipole-forbidden nature of band gap recombination in Cu2O via doping and subsequent insertion of defect states at the band edges with favorable parity for optical transitions (iv) Extending the doping scheme towards ternary Cu-based oxides with novel optical and chemical properties, e.g. CuAlO2 and Cu2V2O7 for the photo-catalytic splitting of water.All experiments are performed with state-of-the art surface-science techniques in an UHV environment, in particular with scanning tunneling and optical nearfield microscopy at the atomic level, and will be accompanied by high-level DFT calculations.