High quality methylammonium bismuth iodide films made using atmospheric pressure chemical vapor deposition.

Ruthenium (Ru) films are deposited using atomic layer deposition (ALD), promoted by a self-catalytic reaction mechanism. Using zero-valent, η 4 -2,3-dimethylbutadiene Ruthenium tricarbonyl (Ru(DMBD)(CO) 3 ) and H 2 O, Ru films are deposited at a rate of 0.1 nm/cycle. The temperature for steady deposition lies between 160 and 210 °C. Film structure and composition are confirmed via X-ray diffraction, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy. The room-temperature electrical resistivity of 10 nm Ru films is found to be 39 μΩ• cm. In situ quadrupole mass spectrometry and density functional theory are used to understand ALD surface reactions. The ligand, dimethylbutadiene dissociatively desorbs on the surface. On the other hand, the carbonyl ligand is catalyzed by the Ru center. This leads to the water gas shift reaction, forming CO 2 and H 2 . Modulating deposition temperature affects these two ligand dissociation reactions. This in turn affects nucleation, growth, and hence, Ru film properties. Self-catalyzed reactions provide a pathway for low-temperature ALD with milder co-reactants.

This article reviews the process-structure-property relationship in doped ZnO thin films via atomic layer deposition (ALD). ALD is an important manufacturing-scalable, layer-by-layer, thin film deposition process that precisely controls dopant type and concentration at the nanoscale. ZnO is an important technological material, which can be doped to modulate structure and composition to tailor a wide variety of optical and electronic properties. ALD doped ZnO is viewed as a transparent conducting oxide for application in solar cells, flexible transparent electronics, and light-emitting diodes. To date, there are 22 elements that have been reported as dopants in ZnO via ALD. This article studies the underlying trends across dopants and establishes generalized relationships for (1) the role of ALD process parameters, (2) the impact of these parameters on the structure of the ZnO matrix, and (3) the impact of dopants on the optical and electrical properties. The article ends with a brief discussion on the limitations of the ALD-based doping scheme, knowledge gaps in the compositional maps, and a perspective on the future of ALD doped ZnO films.

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