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AgCuO2is an interesting semiconductor oxide with appealing optical and electronic properties. While the oxide has been synthesized in bulk by different approaches, no study of the formation mechanism has been carried out to date. We present an in situtime-resolved X-ray diffraction study of the hydrothermal synthesis of AgCuO2from AgO and CuO. The effects of reaction pH and temperature on the reaction pathways and products have been studied. While the pH is a key parameter for the successful synthesis of AgCuO2, the temperature affects mainly the reaction kinetics. A reaction pathway is proposed that involves a series of dissolution–precipitation reactions, mediated by Cu and Ag hydroxy complexes. Finally, we have compared different approaches to obtain the reaction activation energy, which was calculated to be 70.6 ± 5.1 kJ/mol. Nevertheless, our results show that new models need to be developed for the type of reaction presented here.

SiO2constitutes one of the most widely used dielectric materials in the microelectronics, packaging, and optical industries. Therefore, the development of new processes to deposit SiO2at low temperature and in an affordable and scalable way are desirable. In this work, we present a low-temperature, open-air process based on spatial atomic layer deposition (SALD) that yields high purity SiO2films at temperatures down to room temperature. The films were obtained by operating our SALD system in CVD mode (i.e., allowing precursor crosstalk), using an oxygen plasma in combination with trivinylmethoxysilane (TVMS). TVMS is an appealing precursor since it is highly volatile, is affordable, and does not contain halogen elements, thus being very suitable for application in atmospheric-pressure spatial deposition systems. Conversely, water, oxygen, hydrogen peroxide, or ozone did not show any reactivity with TVMS at temperatures up to 260 °C. Thus, when operating our system in ALD mode, no film could be obtained due to the lack of reactivity of the precursor with OH* surface groups. 3D printing was employed to fabricate custom heads integrating both the precursor injector and the atmospheric plasma generator. Our results show that conformal SiO2thin films can be deposited by our atmospheric plasma-enhanced spatial chemical vapor deposition (APE-SCVD) approach at low temperatures (RT–180 °C) on different substrates, including silicon wafers, microglass slides, or even polymeric substrates with a high growth rate up to 2–5 nm/min. The deposition rate increased when increasing the power applied to the plasma reactor but decreased when increasing the deposition temperature due to the faster decay of the metastable oxygen radical species. FTIR results showed no differences for films deposited with different plasma powers. Conversely, temperature had an effect on the ratio between the AS1and the AS2bands. Even though the deposition of SiO2was carried out at low temperatures in the open air using a metalorganic precursor, no contamination from SiNxor SiCxwas observed by FTIR and XPS measurements. Our results open the door to the low-temperature, fast printing of Si-based devices.

Fine control over the growth of materials is required to precisely tailor their properties. Spatial atomic layer deposition (SALD) is a thin-film deposition technique that has recently attracted attention because it allows producing thin films with a precise number of deposited layers, while being vacuum-free and much faster than conventional atomic layer deposition. SALD can be used to grow films in the atomic layer deposition or chemical vapor deposition regimes, depending on the extent of precursor intermixing. Precursor intermixing is strongly influenced by the SALD head design and operating conditions, both of which affect film growth in complex ways, making it difficult to predict the growth regime prior to depositions. Here, we used numerical simulation to systematically study how to rationally design and operate SALD systems for growing thin films in different growth regimes. We developed design maps and a predictive equation allowing us to predict the growth regime as a function of the design parameters and operation conditions. The predicted growth regimes match those observed in depositions performed for various conditions. The developed design maps and predictive equation empower researchers in designing, operating, and optimizing SALD systems, while offering a convenient way to screen deposition parameters, prior to experimentation.

Carbon microfibers make a promising candidate as textile reinforcement for high temperature composites provided that their limitation of thermal oxidation over 670 K in air is overcome. As such, this study explored the potential of atomic layer deposition (ALD) for the deposition of a substrate-nanolaminate interface layer for the design of a refractory oxygen barrier coating applied to individual carbon microfibers within a woven fabric. To this end, amorphous aluminum hydroxide was deposited at 350 K in a flow-type thermal ALD reactor operating at a pressure of 1.8 Torr, yielding a growth per cycle (GPC) of 1.0 Å/cycle. The conformal aspect of the amorphous films was found to be well preserved below a thickness of 45 ± 5 nm, above which reorganization of the substrate surface by junction of the previously deposited layers resulted in a uniform deposition. Furthermore, a minimal thickness of 20 ± 2 nm was required to obtain self-standing films following the thermal oxidation of the carbon microfibers. Indeed, thermal treatment at 1380 K of the coated woven fabric induced multiple occurrences of neat cracks in the aluminum oxide films, attributed to the increased rigidity and mismatch between the respective thermal expansion coefficients. The dense network of nanograins of aluminum oxide was further characterized by using 4D-STEM, revealing multiple phases and orientations.