Fundamental and functional properties of ultra-thin oxide films grown by atomic layer deposition (ALD) studied in-situ by means of surface sensitive techniques

我们进行了系统的原位研究ALD生长的基本和功能特性，使用表面敏感的方法。我们使用ALD基板上定期举行的阶梯状表面在不同的温度和表征的发生和强度的表面扩散的扫描显微镜。我们确定ALD成核网站的分布作为衬底温度和平均平台宽度的函数，给出了定量估计的扩散，以了解其在ALD中的作用。我们将在规则表面上获得的知识应用于多晶衬底，以便找到在复杂表面上沉积平坦膜的实验条件。我们将标准ALD程序应用于具有不同氧化态和晶体结构的氧化物衬底，并通过同步辐射光电子能谱和吸收光谱来表征膜的生长。衬底化学和结构根据其对ALD前体的反应性来改变生长和界面特征。我们确定氧化物衬底的氧化态和晶体结构所起的不同作用，以定制界面，衬底和ALD膜功能后，选择适当的支持材料和ALD参数。这些研究将在现场进行，使用具有极端表面敏感性的表征方法。这种组合在国际上是独一无二的，已经证明可以澄清ALD的意外性质。

We perform a systematic in-situ study of fundamental and functional properties of ALD growth using surface sensitive methods. We use ALD on substrates with regularly stepped surfaces held at various temperatures and characterize the occurrence and strength of surface diffusion by means of scanning microscopy. We determine the distribution of ALD nucleating sites as a function of substrate temperature and average terrace width, giving a quantitative estimation of diffusion for understanding its role in ALD. We apply the knowledge gained on regular surfaces to polycrystalline substrates in order to find the experimental conditions for depositing flat films also on complex surfaces. We apply standard ALD procedures to oxide substrates with different oxidation state and crystalline structure and characterise the film growth by means of Synchrotron radiation photoemission and absorption spectroscopy. Substrate chemistry and structure modify growth and interface features depending on their reactivity towards the ALD precursor. We determine the distinct roles played by oxidation state and crystalline structure of the oxide substrates to tailor interface, substrate and ALD film functionalities upon choice of the appropriate supporting material and ALD parameters. These studies will be done in-situ, using characterization methods with extreme surface sensitivity. Such a combination, unique at international level, has already proven to clarify unexpected properties of ALD.