The doped/alloyed HfO2 and ZrO2 thin films revolutionized not only the field of ferroelectric physics but also various ranges of device applications. Especially when the two oxides are combined in an 1:1 ratio, the ferroelectric polarization of the material became the most distinctive. Many researchers have investigated various different process conditions such as controlling Hf0.5Zr0.5O2 (HZO) film thickness and modifying different metal electrodes. Here, we explored the effect of additional Ar plasma treatment to the HZO film. The additional Ar plasma was exposed to the plasma-enhanced atomic layer deposition (PEALD) HZO for this study. Then, the sample was compared with a conventional PEALD and thermal ALD HZO films. By understanding the polarization–electric field (P–E), current–electric field (I–E), and electrical breakdown characteristics of the different samples, it was found that the Ar plasma treatment can control the degree of ferroelectric and antiferroelectric phases of HZO film.

In the past decade, atomic and molecular layer deposition (ALD and MLD), these two sister techniques have been attracting more and more research attention to address technical challenges in various advanced battery systems. The charm of both ALD and MLD lies in their unique mechanism for growing a large variety of functional materials, featuring uniform and conformal films enabled at the atomic/molecular level at low temperature. Using ALD and MLD, to date, there have been many excitements achieved in research. These will ultimately be reflected on technical innovations that will help revolutionize our lifestyles. This invited article gives the first comprehensive review briefing on the journey of ALD and MLD in pursuing better batteries and highlighting many exciting progresses in various advanced battery systems. It is expected that this review will help boost many more efforts in using ALD and MLD for new battery technologies in the coming decade.

LiMnxCoyNi1−x−yO2 (LMCNO) has been broadly investigated and commercialized primarily as lithium ion battery (LIB) cathodes, owing to its high operating voltage, large energy density, and superior electronic conductivity. However, poor cycling stability induced by the rapid structure degradation limits their further development. Coating is regarded as a very effective strategy to address the problem of structure degradation. Regrettably, the coating layers obtained by traditional methods are usually thick, which is not appropriate for delivering of integrated performance. As an emerging coating technology, atomic layer deposition (ALD) demonstrates immeasurable advantages in deposition of ultrathin coating materials because of its atomic-level precision, and has been widely applied in construction of the coating layers on LMCNO substrate materials. Herein, we firstly outline the development and mechanism of ALD technology, and then systematically summarize intrinsic reasons for the enhanced electrochemical performance. Finally, we propose new insights toward designing and preparing the coating structure of LMCNO cathodes by controllable ALD for the next-generation LIBs.

SiC and Ga2O3 are promising wide band gap semiconductors for applications in power electronics because of their high breakdown electric field and normally off operation. However, lack of a suitable dielectric material that can provide high interfacial quality remains a problem. This can potentially lead to high leakage current and conducting loss. In this work, we present a novel atomic layer deposition process to grow epitaxially MgxCa1−xO dielectric layers on 4H-SiC(0001) and β-Ga2O3$\left( {\bar 201} \right)$ substrates. By tuning the composition of MgxCa1−xO toward the substrate lattice constant, better interfacial epitaxy can be achieved. The interfacial and epitaxy qualities were investigated and confirmed by cross-sectional transmission electron microscopy and X-ray diffraction studies. Mg0.72Ca0.28O film showed the highest epitaxy quality on 4H-SiC(0001) because of its closest lattice match with the substrate. Meanwhile, highly textured Mg0.25Ca0.75O films can be grown on β-Ga2O3$\left( {\bar 201} \right)$ with a preferred orientation of (111).

To solve the poor cyclability of faradic supercapacitors (SCs), the authors reported a unique porous carbon (PC) coating with “gap shell” structure on carbon fiber cloth (CFC)/NiS2 materials. This gap shell PC coating was fabricated by combining atomic layer deposition (ALD) Al2O3 and molecular layer deposition alucone, followed by carbonization and etching. The as-prepared CFC/NiS2/PC composites were directly used as binder-free electrodes for SCs. Benefited from its novel nanostructure, the CFC/NiS2/PC electrode shows a large specific capacitance of 1034.6 F/g at 1 A/g and considerable rate capability of 67% capacitance, retaining ratio within 1–20 A/g. The cyclability of the CFC/NiS2/PC electrode is enhanced by 50% relative to the mere CFC/NiS2 after 2000 cycles, which is attributed to the gap and electrically conductive PC coating. Hence, this work provides a promising approach to design gap shell layer for improved cyclability of faradic SCs and other practical applications in energy storage electronics.

Na–Se batteries are promising energy storage systems for grid and transportation applications, due to the high volumetric energy density and relatively low cost. However, the development of Na–Se batteries has been hindered by the shuttle effect originating from polyselenide dissolution from the Se cathode. Herein, we reported the utilization of nanoscale Al2O3 surface coating by atomic layer deposition (ALD) to protect a microporous carbon/Se (MPC/Se) cathode and reduce polyselenide dissolution. Compared with the pristine MPC/Se, Al2O3-coated MPC/Se cathode exhibited improved discharge capacity, cycling stability, and rate capability in Na–Se batteries. Post-cycling analysis disclosed that Al2O3 coating on MPC/Se cathode effectively suppressed the polyselenide dissolution, facilitated the formation of thin and stable solid electrolyte interphase (SEI) layers, and reduced charge transfer resistance, thus improving the overall performance of Na–Se batteries. This work suggests the effectiveness of interface control by ALD in enabling high-performance Na–Se batteries and might shed light on the development of new-generation Li/Na/K-chalcogenide batteries.

Amorphous carbon, germanium oxide, and 2-dimensional transition metal dichalcogenides grown by atomic layer deposition (ALD) are considered as promising materials for advanced nanoscale device fabrication processes and electronic devices, owing to their extraordinary characteristics. Deposition of these materials using ALD can overcome the limitations of current deposition techniques, including poor step coverage and wafer-scale uniformity, and uncontrollable stoichiometry. Despite these advantages, there has been a lack of research into these materials due to the absence of suitable precursors or optimized processes. In this review, we focus on these nonconventional materials, which have rarely been studied using ALD. The latest research progress and future outlook on these materials grown by ALD will be highlighted, with a particular focus on the applications of future nanoscale device fabrication processes and new concepts in device fabrication which could lead to a paradigm shift in electronics.

A multilevel nonvolatile memory based on an amorphous indium–gallium–zinc oxide thin-film transistor is successfully demonstrated by using an atomic layer–deposited ZnO film as a charge trapping layer. The memory device shows a much higher erasing efficiency at a negative bias, i.e., after erasing at −13 V for 1 μs, the threshold voltage shift is as large as −7.4 V. In the case of 13 V/1 μs programming (P) and −12 V/1 μs erasing (E), the device demonstrates an ON/OFF readout drain current (IDS) ratio of ∼103 after 105 s, and a large and stable ON/OFF IDS ratio of ∼106 till 104 of P/E cycles. Furthermore, multilevel memory characteristics are also demonstrated on the device, showing an IDS ratio of >102 for 4 different states. Additionally, the device also successfully demonstrates typical synaptic behaviors, such as excitatory and inhibitory postsynaptic current with different memory times at different memory states.

We deposit films of tin–calcium sulfide by atomic layer deposition (ALD) and demonstrate the metastability of this material. Rough and spiky films are obtained by using Sn and Ca precursors with different ligands, whereas compact and smooth films are obtained when the two metal sources share the same ligands. Compositional and quartz crystal microbalance results indicate that part of the underlaying SnS film is replaced and/or removed during the CaS ALD cycle during the ternary film deposition, possibly via a temperature-dependent cation exchange mechanism. The crystal structure transforms from orthorhombic to cubic as the calcium content increases. Furthermore, resistivity increases with calcium content in the alloy films, whereas optical band gap only depends weakly on Ca content. After annealing at 400 °C in an H2S environment, the cubic alloy film undergoes a phase transition into the orthorhombic phase and its resistivity also decreases. Both phenomena could be explained by phase separation of the metastable alloy.

Organic light-emitting diodes (OLEDs) have aroused great attention due to the advantages of high luminescent efficiency, fast response time, wide viewing angle, and the compatibility with the flexible electronics. Nevertheless, the organic luminescent materials are vulnerable to environment moisture/oxygen. Thus, how to protect the OLEDs from the ambient moisture/oxygen erosion is of great importance to ensure the stability and reliability. Thin film encapsulation (TFE) via atomic layer deposition (ALD) has emerged as a potential method to meet the encapsulation requirements of OLEDs due to its unique assets. In this review, the challenges of TFE, including pinholes, crystallization, cracks, and overheated, are introduced first. The ALD-based monolayer, composite structures, and hybrid laminates were developed to improve the barrier property, flexibility, and thermal conductivity. Besides, the ALD reactors and processes for TFE are also reviewed. Finally, the challenges remained and future development in the stabilization of OLEDs via ALD are also discussed.

Capacitors represent the largest obstacle to dynamic random-access memory (DRAM) technology evolution because the capacitor properties govern the overall operational characteristics of DRAM devices. Moreover, only the atomic layer deposition (ALD) technique is used for the dielectric and electrode because of its extreme geometry. Various high-k materials deposited by ALD have been investigated for further scaling. Whereas past investigations focused on increasing the physical thickness of the dielectric to suppress leakage current, the physical thickness of the dielectric should also be limited to a few nanometers in design rules less than 1×-nm. Therefore, a new way to overcome the limitations of traditional approaches based on thorough understanding of high-k materials is highly recommended to enhance the properties of conventional materials and provide directions for developing new materials. In this review, previously reported results are discussed, and suggestions are made for further investigations for DRAM capacitor applications.

In this work, we studied an atomic layer deposition (ALD) process of ZrO2 with the precursors of tetrakis(dimethylamido)zirconium(IV) and water. We investigated the growth characteristics and mechanism of the ALD ZrO2 in the temperature range of 50–275 °C. Furthermore, the evolutions of film thickness and morphology were studied and discussed. It was found that the growth rate of ZrO2 decreased almost linearly with the increasing temperature from ∼1.81 Å/cycle at 50 °C to ∼0.8 Å/cycle at 225 °C. Interestingly, it was revealed that the growth of ZrO2 films ceased after a certain number of ALD cycles at a temperature higher than 250 °C. We also verified that the crystallinity of ZrO2 evolved with deposition temperature from amorphous to crystalline phase. In addition, the wettability of ZrO2 films was studied, showing a hydrophobic nature.

Developing low-cost and high-performance hydrogen evolution reaction (HER) electrocatalysts is essential for the development of hydrogen energy. While transition metal sulfides are reported as promising HER electrocatalysts, their performance still requires further improvement for practical application. In this work, we report a strategy to construct NiSx@MoS2 heterostructures with a well-defined interface structure by growing NiSx nanoclusters on MoS2 nanosheets through atomic layer deposition (ALD). NiSx@MoS2 heterostructures exhibit strongly enhanced HER activity with lower overpotential and faster reaction dynamic compared to MoS2 and NiSx single phases. The enhanced performance is attributed to improved adsorption of the reaction intermediates and the facilitated charge transfer process near the MoS2/NiSx interfaces. Besides high activity, NiSx@MoS2 heterostructures also exhibit high stability in alkaline media. The methodology and knowledge in this work can guide the rational design of high-performance electrocatalysts through hetero-interface engineering.

Al-doped ZnO (AZO) is a promising earth-abundant alternative to Sn-doped In2O3 (ITO) as an n-type transparent conductor for electronic and photovoltaic devices. We have deposited AZO films with resistivities as low as 1.1 × 10−3 Ω·cm by atomic layer deposition (ALD) using trimethylaluminum (TMA), diethylzinc (DEZ), and water at 200 °C. The work functions of the films were measured using a scanning Kelvin probe (sKP) to investigate the role of aluminum concentration. The work function of AZO films prepared by two different ALD recipes were compared: a “Al-terminated” recipe and a “ZnO-terminated” recipe. As aluminum doping increases, the Al-terminated recipe produces films with a consistently higher work function than the ZnO-terminated recipe. The resistivity of the Al-terminated recipe films shows a minimum at a 1:16 Al:Zn atomic ratio and using a ZnO-terminated recipe, minimum resistivity was seen at 1:19. The film thicknesses were characterized by ellipsometry, chemical composition by EDX, and resistivity by a four-point probe.

Nanostructures are considered to have great potential and are widely used in energy storage and sensing devices, and atomic layer deposition (ALD) is of great help for better nanostructure fabrications. ALD can help to preserve the original properties of materials, and, meanwhile, the excellent film quality, nanoscale precise thickness control, and high conformality also play important role in fabrication process. To enhance the performance of energy storage and sensor devices, ALD has been used in directly fabricating active nanostructures, depositing protective passivation layers, etc. ALD is a convenient technique which has been widely engaged in energy-related fields including electrochemical conversion and storage, as well as in sensor and biosensors. The related research interest is increasing significantly. In this review, we summarize some of the latest works on ALD for batteries, supercapacitors, and sensors, and demonstrate the benefits of ALD comprehensively. In these devices, different materials are deposited by ALD under different conditions to achieve better battery performance, higher supercapacitor capacitance, and higher sensitivity. This review fully presents the strengths of ALD and its application in energy storage and sensing devices and proposes the future prospects for this rapidly developing technology.

The initial steps of the thermal chemistry of Cu(I)-2-(tert-butylimino)-5,5-dimethyl-pyrrolidinate on metal surfaces were characterized using temperature-programmed desorption experiments and density functional theory (DFT). The relative stability of the initial dimer relative to its dissociation on metal surfaces was evaluated. Several molecular desorption temperatures were identified on Ni(110), but all correspond to dimers, either containing the initial Cu ions or after their removal; no monomer was ever detected. DFT calculations also indicated preferential bonding on Cu(110) as a dimer, albeit with a distorted configuration, via the Cu atoms and in registry with the lattice of the substrate. A potential dissociation pathway of the adsorbed dimer was identified involving the partial detachment of the ligands via the scission of one Cu–N bond at the time and migration to adjacent surface sites. This process is accompanied by the reduction of the Cu centers of the metal–organic complex, indicating that it may be the rate-limiting reaction that leads to further fragmentation of the ligands.

In this work, atomic layer deposition (ALD), as a novel strategy, has been applied to deposit MgO on nano-sized porous Si (pSi) dendrites obtained by etching Al–Si alloy for LIBs. The reversible specific capacity of pSi@MgO electrode is 969.4 mA h/g after 100 cycles at 100 mA/g between 0.01 and 1.5 V, and it presents the discharge specific capacities of 1253.0, 885.5, 642.4, 366.2, and 101.4 mA h/g at 100, 500, 1000, 2000, and 5000 mA/g, respectively. What is more, it delivers a high reversible capacity of 765.1 mA h/g even at 500 mA/g after 200 cycles. The performance improvement can be attributed to the protection of the MgO layer and built-in space of porous Si for volume expansion upon cycling. These results illustrate that ALD derived coating is a powerful strategy to enhance electrical properties of anode materials with huge volume change for lithium-ion batteries.

More than 1 million tons of oil is inadvertently spilled each year. The economic and environmental costs of these spills are enormous and compel further development of environmentally friendly sorbent materials. Here, we demonstrate a vapor-phase modification approach to create a new class of oil sorbents composed of cellulosic materials (cotton) coated with a subnanometer layer of inorganic oxide. This new cellulosic sorbent remains buoyant in water indefinitely and achieves a selective oil sorption capacity (23 g/g or 1.05 g/cm3) that is at least 35 times better than untreated cellulose in aqueous environments. This new sorbent particularly excels under “realistic” conditions such as continuous agitation (e.g., simulated waves) and presoaking in water (e.g., rain or forced immersion). When sorption performance is compared on a per-volume basis—which better captures use conditions than a per-mass basis—this modified natural product becomes comparable to the best sorbents reported in the literature.

We have investigated the chemical and electrical properties of a thin SiO2/TiO2 stacking layer deposited on n-Si and heavily phosphorus-doped n++ Si substrates to elucidate effects of phosphorus doping of Si absorbers on the band alignment and electrical performance of a SiO2/TiO2 stack-based electron-selective contact deposited on the differently doped Si substrates. From our XPS study, we show a shift of the TiO2 energy levels up to ∼0.13 eV with respect to those of Si as the doping level of Si substrates changes. We also show that the conduction band offset of the SiO2/TiO2 stacking layer at the interface with the n++ Si substrate seems to smaller than that of the SiO2/TiO2 stacking layer at the interface with n-Si substrate. Finally, from our electrical transport measurements, we could conclude that the thinner tunneling barrier, the increased electron density in front of the SiO2 layer in the n++ Si surface, and/or the reduced barrier height by heavy doping, seem to enhance the majority electron transport property of the SiO2/TiO2/n++ Si samples compared to that of the SiO2/TiO2/n-Si samples.

Atomic layer deposition (ALD) of air stable cobalt and nickel complexes based on tridentate enaminones N,N-(4,4,4-trifluorobut-1-en-3-on)-dimethylethyldiamine (Htfb-dmeda) and N,N-(4,4,4-trifluorobut-1-en-3-on)-dimethylpropyldiamine (Htfb-dmpda) successfully produced metallic cobalt and nickel thin films. Detailed X-ray photoelectron spectroscopy (XPS) studies on the binding interaction of the first precursor monolayer with the surface functional groups elucidated the chemisorption behavior of the new precursor systems. A reactive remote hydrogen plasma was used as the co-reactant to activate the precursor decomposition yielding metal hydroxide intermediates. Subsequent hydrogen plasma etching of as-deposited films resulted in phase-pure metallic films through a recrystallization process, verified by surface and sub-surface XPS. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) analyses revealed pinhole-free films, with low surface roughness (0.2 ± 0.06 nm root mean square, RMS) for both, cobalt and nickel thin films. Herein, the competitive role of hydrogen as etchant and reactant was demonstrated as prolonged plasma exposure time periods resulted in the formation of metal hydrides. This is mostly due to the catalytic dissociation of molecular hydrogen on transition metal surfaces, which already occurs upon low energy input.