Atmospheric pressure spatial atomic layer deposition (AP-SALD) has recently emerged as an appealing technique for rapidly producing high quality oxides. Here, we focus on the use of AP-SALD to deposit functional ZnO thin films, particularly on the reactors used, the film properties, and the dopants that have been studied. We highlight how these films are advantageous for the performance of solar cells, organometal halide perovskite light emitting diodes, and thin-film transistors. Future AP-SALD technology will enable the commercial processing of thin films over large areas on a sheet-to-sheet and roll-to-roll basis, with new reactor designs emerging for flexible plastic and paper electronics.

Atmospheric-pressure atomic layer deposition (ALD) is an upcoming technology poised to revolutionize the commercial production of large-area substrates and unlock new applications in high-porosity/3D materials.

A first‐of‐its‐kind area‐selective deposition process for SiO₂ is developed consisting of film deposition with interleaved exposures to small molecule inhibitors (SMIs) and back‐etch correction steps, within the same spatial atomic layer deposition (ALD) tool. The synergy of these aspects results in selective SiO₂ deposition up to ~23 nm with high selectivity and throughput, with SiO₂ growth area and ZnO nongrowth area. The selectivity is corroborated by both X‐ray photoelectron spectroscopy (XPS) and low‐energy ion scattering spectroscopy (LEIS). The selectivity conferred by two different SMIs, ethylbutyric acid, and pivalic acid has been compared experimentally and theoretically. Density Functional Theory (DFT) calculations reveal that selective surface functionalization using both SMIs is predominantly controlled thermodynamically, while the better selectivity achieved when using trimethylacetic acid can be explained by its higher packing density compared to ethylbutyric acid. By employing the trimethylacetic acid as SMI on other starting surfaces (Ta₂O₅, ZrO₂, etc.) and probing the selectivity, a broader use of carboxylic acid inhibitors for different substrates is demonstrated. It is believed that the current results highlight the subtleties in SMI properties such as size, geometry, and packing, as well as interleaved back‐etch steps, which are key in developing ever more effective strategies for highly selective deposition processes.

To date, conventional thermal atomic layer deposition (ALD) has been the method of choice to deposit high-quality Pt thin films grown typically from (MeCp)PtMe₃ vapor and O₂ gas at 300 °C. Plasma-assisted ALD of Pt using O₂ plasma can offer several advantages over thermal ALD, such as faster nucleation and deposition at lower temperatures. In this work, it is demonstrated that plasma-assisted ALD at 300 °C also allows for the deposition of highly conformal Pt films in trenches with high aspect ratio ranging from 3 to 34. Scanning electron microscopy inspection revealed that the conformality of the deposited Pt films was 100% in trenches with aspect ratio (AR) up to 34. These results were corroborated by high-precision layer thickness measurements by transmission electron microscopy for trenches with an aspect ratio of 22. The role of the surface recombination of O-radicals and the contribution of thermal ALD reactions is discussed.

Atmospheric-pressure Plasma-Enhanced spatial Atomic Layer Deposition (PE-s-ALD) is a high-throughput technique for synthesizing thin films at low temperatures for large area applications. The spatial separation of the ALD half-reactions and the use of an atmospheric pressure plasma as the reactant give rise to complex surface chemistry which is not yet well understood. Here, we employed gas-phase infrared spectroscopy and optical emission spectroscopy (OES) to study the underlying chemistry of the PE-s-ALD process of Al₂O₃ films grown at 80 °C using Al(CH₃)₃ and an Ar-O₂ plasma. We identified the reaction products and investigated their dependence on the exposure time of the substrate to the precursor. Infrared absorbance spectra show CO, CO₂, H₂O, and CH₄ as the main ALD reaction byproducts originating from (i) combustion-like reactions of the methylated surface with O plasma radicals and O₃ and (ii) a concurrent latent thermal ALD component due to produced and/or residual H₂O molecules. In addition, CH₂O and CH₃OH were identified as reaction by-products either originating at the surface or formed in the plasma. The OES spectra provide a corroborative proof of the combustive nature of the PE-s-ALD reactions showing OH and CH emissions arising during the spatial ALD process while excited O species are being consumed.

Compared to conventional NAND flash resistive switching metal-oxide cells show a number of advantages, like an increased endurance, lower energy consumption, and superior switching speed. Understanding the role of defects for the resistive switching phenomenon in metal oxides is crucial for their improvement and thereby also for their acceptance as a next generation data storage device. Strontium titanate (STO) is considered a model material due to its thoroughly investigated defect chemistry. This paper presents a comparative study of the switching kinetics for three different compositions [Sr]/([Sr]+[Ti]) of 0.57 (Sr-rich), 0.50 (stoichiometric STO), and 0.46 (Ti-rich STO). The STO films, deposited by atomic layer deposition, were integrated in Pt/STO/TiN nanocrossbars with a feature size of 100 nm. By analysis of the transient currents, the switching kinetics are investigated between 10 ns and 10⁴s for the SET and 10 ns and 100 s for the RESET. A clear influence of the composition on the degree of nonlinearity of the switching kinetics was observed. Applying an analytical model for the oxygen vacancy migration, we were able to explain the differences in the SET kinetics by composition-dependent changes in the thermal conductivity and by a lower activation energy for the Ti-rich sample. This might be utilized in design rules of future ReRAM devices.