Showing papers on "Atomic layer deposition published in 2014"
TL;DR: Atomic layer deposition (ALD) is a vapor phase technique capable of producing thin films of a variety of materials as discussed by the authors, including metal oxides such as Zn1−xSnxOy, ZrO2, Y2O3, and Pt.
1,280 citations
TL;DR: It is shown that TiO2 coatings grown by atomic layer deposition prevent corrosion, have electronic defects that promote hole conduction, and are sufficiently transparent to reach the light-limited performance of protected semiconductors.
Abstract: Although semiconductors such as silicon (Si), gallium arsenide (GaAs), and gallium phosphide (GaP) have band gaps that make them efficient photoanodes for solar fuel production, these materials are unstable in aqueous media. We show that TiO2 coatings (4 to 143 nanometers thick) grown by atomic layer deposition prevent corrosion, have electronic defects that promote hole conduction, and are sufficiently transparent to reach the light-limited performance of protected semiconductors. In conjunction with a thin layer or islands of Ni oxide electrocatalysts, Si photoanodes exhibited continuous oxidation of 1.0 molar aqueous KOH to O2 for more than 100 hours at photocurrent densities of >30 milliamperes per square centimeter and ~100% Faradaic efficiency. TiO2-coated GaAs and GaP photoelectrodes exhibited photovoltages of 0.81 and 0.59 V and light-limiting photocurrent densities of 14.3 and 3.4 milliamperes per square centimeter, respectively, for water oxidation.
1,117 citations
TL;DR: An overview of the current state of ZnO ALD research including the applications that are being considered for thin-film applications can be found in this article, where the authors present a review of the state-of-the-art applications of ALD-based thin-filters.
Abstract: Due to the unique set of properties possessed by ZnO, thin films of ZnO have received more and more interest in the last 20?years as a potential material for applications such as thin-film transistors, light-emitting diodes and gas sensors. At the same time, the increasingly stringent requirements of the microelectronics industry, among other factors, have led to a dramatic increase in the use of atomic layer deposition (ALD) technique in various thin-film applications. During this time, the research on ALD-grown ZnO thin films has developed from relatively simple deposition studies to the fabrication of increasingly intricate nanostructures and an understanding of the factors affecting the fundamental properties of the films. In this review, we give an overview of the current state of ZnO ALD research including the applications that are being considered for ZnO thin films.
336 citations
TL;DR: In this article, the authors employed atomic layer deposition (ALD) to coat lithium tantalum oxide, a solid-state electrolyte, with varying thicknesses on NMC in an attempt to improve battery performance.
Abstract: LiNi1/3Co1/3Mn1/3O2 (NMC) is a highly promising cathode material for use in lithium ion batteries; unfortunately, its poor cycling performance at high cutoff voltages hinders its commercialization. In this study, for the first time, we employ atomic layer deposition (ALD) to coat lithium tantalum oxide, a solid-state electrolyte, with varying thicknesses on NMC in an attempt to improve battery performance. Our results indicate that utilization of a solid-state electrolyte as a coating material for NMC significantly improves performance at high cutoff voltages but is strongly dependent on coating thicknesses. Our investigation revealed that a thicker coating proved to be beneficial in preventing cathode material dissolution into the electrolyte and aided in maintaining the microstructure of NMC. Consequently, a thicker ALD coating resulted in increased electrochemical impedance of the cathode. The results of this study indicate that an optimized coating thickness is needed in order to strike a balance between maintaining structural stability while minimizing electrochemical impedance. The coating thicknesses are functionally specific, and for the best improvement of a cathode, a particular coating thickness should be sought.
331 citations
TL;DR: In this paper, an atomic layer deposition (ALD) technique was used to grow a multilayer MoS film at 300 °C on a sapphire wafer, which exhibited strong photoluminescence in the visible range.
Abstract: A mono- to multilayer thick MoS₂ film has been grown by using the atomic layer deposition (ALD) technique at 300 °C on a sapphire wafer. ALD provides precise control of the MoS₂ film thickness due to pulsed introduction of the reactants and self-limiting reactions of MoCl₅ and H₂S. A post-deposition annealing of the ALD-deposited monolayer film improves the crystallinity of the film, which is evident from the presence of triangle-shaped crystals that exhibit strong photoluminescence in the visible range.
310 citations
TL;DR: A logical comparison of the relative defect densities of Zn(i)s and V(O)s suggested that the former are less efficient than the latter because of the differences in the intrinsic nature and the physical accessibility of the defects.
Abstract: Oxygen vacancies (VOs) in ZnO are well-known to enhance photocatalytic activity (PCA) despite various other intrinsic crystal defects. In this study, we aim to elucidate the effect of zinc interstitials (Zni) and VOs on PCA, which has applied as well as fundamental interest. To achieve this, the major hurdle of fabricating ZnO with controlled defect density requires to be overcome, where it is acknowledged that defect level control in ZnO is significantly difficult. In the present context, we fabricated nanostructures and thoroughly characterized their morphological (SEM, TEM), structural (XRD, TEM), chemical (XPS) and optical (photoluminescence, PL) properties. To fabricate the nanostructures, we adopted atomic layer deposition (ALD), which is a powerful bottom-up approach. However, to control defects, we chose polysulfone electrospun nanofibers as a substrate on which the non-uniform adsorption of ALD precursors is inevitable because of the differences in the hydrophilic nature of the functional groups. For the first 100 cycles, Znis were predominant in ZnO quantum dots (QDs), while the presence of VOs was negligible. As the ALD cycle number increased, VOs were introduced, whereas the density of Zni remained unchanged. We employed PL spectra to identify and quantify the density of each defect for all the samples. PCA was performed on all the samples, and the percent change in the decay constant for each sample was juxtaposed with the relative densities of Znis and VOs. A logical comparison of the relative defect densities of Znis and VOs suggested that the former are less efficient than the latter because of the differences in the intrinsic nature and the physical accessibility of the defects. Other reasons for the efficiency differences were elaborated.
302 citations
TL;DR: In this article, an atomic layer deposition (ALD) method has been employed to synthesize Fe3O4/graphene and Ni/Graphene composites and the structure and microwave absorbing properties of the as-prepared composites are investigated.
Abstract: An atomic layer deposition (ALD) method has been employed to synthesize Fe3O4/graphene and Ni/graphene composites. The structure and microwave absorbing properties of the as-prepared composites are investigated. The surfaces of graphene are densely covered by Fe3O4 or Ni nanoparticles with a narrow size distribution, and the magnetic nanoparticles are well distributed on each graphene sheet without significant conglomeration or large vacancies. The coated graphene materials exhibit remarkably improved electromagnetic (EM) absorption properties compared to the pristine graphene. The optimal reflection loss (RL) reaches −46.4 dB at 15.6 GHz with a thickness of only 1.4 mm for the Fe3O4/graphene composites obtained by applying 100 cycles of Fe2O3 deposition followed by a hydrogen reduction. The enhanced absorption ability arises from the effective impedance matching, multiple interfacial polarization and increased magnetic loss from the added magnetic constituents. Moreover, compared with other recently reported materials, the composites have a lower filling ratio and smaller coating thickness resulting in significantly increased EM absorption properties. This demonstrates that nanoscale surface modification of magnetic particles on graphene by ALD is a very promising way to design lightweight and high-efficiency microwave absorbers.
284 citations
TL;DR: In this paper, a review of thermal ALD of noble metals and their oxides is presented, where reaction mechanisms in various types of processes are discussed and issues in nucleation are addressed.
Abstract: Atomic layer deposition (ALD) is an attractive method to deposit thin films for advanced technological applications such as microelectronics and nanotechnology. One material group in ALD that has matured in 10 years and proven to be of wide technological importance is noble metals. In this paper, thermal ALD of noble metals and their oxides is reviewed. Noble metal films are mostly grown using O2 as the nonmetal precursor in a combustion-type chemistry. Alternatively, lower growth temperatures can be reached via noble metal oxide growth with consecutive reactions with ozone and H2. The use of true reducing chemistry (i.e., H2) is typical only for ALD of palladium at low temperatures. On the other hand, ALD of noble metal oxides has been limited with reactants such as ozone and O2 gas. In this review, reaction mechanisms in various types of processes are discussed and issues in nucleation are addressed. Deposition temperatures, film growth rates, and purities as well as evaporation temperatures used for no...
282 citations
TL;DR: The use of ALD as an enabling technology in advanced nanopatterning methods such as spacer defined double patterning or block copolymer lithography is discussed, as well as the application of selective ALD in self-aligned fabrication schemes.
Abstract: Atomic layer deposition (ALD) is a method that allows for the deposition of thin films with atomic level control of the thickness and an excellent conformality on 3-dimensional surfaces. In recent years, ALD has been implemented in many applications in microelectronics, for which often a patterned film instead of full area coverage is required. This article reviews several approaches for the patterning of ALD-grown films. In addition to conventional methods relying on etching, there has been much interest in nanopatterning by area-selective ALD. Area-selective approaches can eliminate compatibility issues associated with the use of etchants, lift-off chemicals, or resist films. Moreover, the use of ALD as an enabling technology in advanced nanopatterning methods such as spacer defined double patterning or block copolymer lithography is discussed, as well as the application of selective ALD in self-aligned fabrication schemes.
276 citations
276 citations
TL;DR: A new and highly reproducible and controllable technique for improving battery performance by utilizing atomic layer deposition to surface engineer SnO2 nanowires, resulting in a new type of hollowed SnO 2- in-TiO2 wire-in-tube nanostructure.
Abstract: SnO2 nanowires directly grown on flexible substrates can be a good electrode for a lithium ion battery. However, Sn-based (metal Sn or SnO2) anode materials always suffer from poor stability due to a large volume expansion during cycling. In this work, we utilize atomic layer deposition (ALD) to surface engineer SnO2 nanowires, resulting in a new type of hollowed SnO2-in-TiO2 wire-in-tube nanostructure. This structure has radically improved rate capability and cycling stability compared to both bare SnO2 nanowires and solid SnO2@TiO2 core-shell nanowire electrodes. Typically a relatively stable capacity of 393.3 mAh/g has been achieved after 1000 charge-discharge cycles at a current density of 400 mA/g, and 241.2 mAh/g at 3200 mA/g. It is believed that the uniform hollow TiO2 shell provides stable surface protection and the appropriate-sized gap effectively accommodates the expansion of the interior SnO2 nanowire. This ALD-enabled method should be general to many other battery anode and cathode materials, providing a new and highly reproducible and controllable technique for improving battery performance.
TL;DR: The first proof-of-concept experiments in which the newly developed MLD and ALD/MLD processes are exploited to fabricate novel multilayer and nanostructure architectures by combining different inorganic, organic and hybrid material layers into on-demand designed mixtures, superlattices and nanolaminates are discussed.
Abstract: The possibility to deposit purely organic and hybrid inorganic–organic materials in a way parallel to the state-of-the-art gas-phase deposition method of inorganic thin films, i.e., atomic layer deposition (ALD), is currently experiencing a strongly growing interest. Like ALD in case of the inorganics, the emerging molecular layer deposition (MLD) technique for organic constituents can be employed to fabricate high-quality thin films and coatings with thickness and composition control on the molecular scale, even on complex three-dimensional structures. Moreover, by combining the two techniques, ALD and MLD, fundamentally new types of inorganic–organic hybrid materials can be produced. In this review article, we first describe the basic concepts regarding the MLD and ALD/MLD processes, followed by a comprehensive review of the various precursors and precursor pairs so far employed in these processes. Finally, we discuss the first proof-of-concept experiments in which the newly developed MLD and ALD/MLD processes are exploited to fabricate novel multilayer and nanostructure architectures by combining different inorganic, organic and hybrid material layers into on-demand designed mixtures, superlattices and nanolaminates, and employing new innovative nanotemplates or post-deposition treatments to, e.g., selectively decompose parts of the structure. Such layer-engineered and/or nanostructured hybrid materials with exciting combinations of functional properties hold great promise for high-end technological applications.
TL;DR: The selective functionalization of graphene defect sites, together with the nanowire morphology of deposited Pt, yields a superior platform for sensing applications and high-performance hydrogen gas sensors at room temperature are demonstrated.
Abstract: One-dimensional defects in graphene have a strong influence on its physical properties, such as electrical charge transport and mechanical strength. With enhanced chemical reactivity, such defects may also allow us to selectively functionalize the material and systematically tune the properties of graphene. Here we demonstrate the selective deposition of metal at chemical vapour deposited graphene’s line defects, notably grain boundaries, by atomic layer deposition. Atomic layer deposition allows us to deposit Pt predominantly on graphene’s grain boundaries, folds and cracks due to the enhanced chemical reactivity of these line defects, which is directly confirmed by transmission electron microscopy imaging. The selective functionalization of graphene defect sites, together with the nanowire morphology of deposited Pt, yields a superior platform for sensing applications. Using Pt–graphene hybrid structures, we demonstrate high-performance hydrogen gas sensors at room temperature and show its advantages over other evaporative Pt deposition methods, in which Pt decorates the graphene surface non-selectively. Defects in graphene strongly influence the material's physical properties, leading to the suggestion that defects might be tuned to improve performance. Here, via atomic layer deposition, the authors selectively deposit Pt at graphene line defects and yield a superior platform for sensing applications.
TL;DR: The power conversion efficiency of solar cells based on copper (I) oxide (Cu2 O) is enhanced by atomic layer deposition of a thin gallium oxide (Ga2 O3 ) layer that exhibits an open-circuit voltage and efficiency of 3.97%, showing potential of over 7% efficiency.
Abstract: The power conversion efficiency of solar cells based on copper (I) oxide (Cu2 O) is enhanced by atomic layer deposition of a thin gallium oxide (Ga2 O3 ) layer. By improving band-alignment and passivating interface defects, the device exhibits an open-circuit voltage of 1.20 V and an efficiency of 3.97%, showing potential of over 7% efficiency.
TL;DR: Through selective passivation of the defects by atomic layer deposition (ALD) an enhanced corrosion protection of more than 99% was achieved, which compares favorably with commercial corrosion protection methods.
Abstract: Graphene is expected to enable superior corrosion protection due to its impermeability and chemical inertness. Previous reports, however, demonstrate limited corrosion inhibition and even corrosion enhancement of graphene on metal surfaces. To enable the reliable and complete passivation, the origin of the low inhibition efficiency of graphene was investigated. Combining electrochemical and morphological characterization techniques, nanometer-sized structural defects in chemical vapor deposition grown graphene were found to be the cause for the limited passivation effect. Extremely fast mass transport on the order of meters per second both across and parallel to graphene layers results in an inhibition efficiency of only ∼50% for Cu covered with up to three graphene layers. Through selective passivation of the defects by atomic layer deposition (ALD) an enhanced corrosion protection of more than 99% was achieved, which compares favorably with commercial corrosion protection methods.
TL;DR: In this paper, the effects of the metal oxide coatings on the electrochemical performance of LiCoO2 electrode are studied in detail, and it is shown that a uniform and dense coating via the ALD route on LiO2 powder can lower the battery performance due to an obvious decrease in lithium diffusion and electron transport with the coating layers.
TL;DR: It was shown that annealing at 800 °C substantially improves the water oxidation efficiency of the ultrathin film hematite electrodes, and the effect of high temperature treatment is shown to remove one of two surface states identified, which reduces recombination and Fermi level pinning.
Abstract: Hematite (α-Fe2O3) thin film electrodes prepared by atomic layer deposition (ALD) were employed to photocatalytically oxidize water under 1 sun illumination. It was shown that annealing at 800 °C substantially improves the water oxidation efficiency of the ultrathin film hematite electrodes. The effect of high temperature treatment is shown to remove one of two surface states identified, which reduces recombination and Fermi level pinning. Further modification with Co–Pi water oxidation catalyst resulted in unprecedented photocurrent onset potential of ∼0.6 V versus reversible hydrogen electrode (RHE; slightly positive of the flat band potential).
TL;DR: This tutorial review describes some unique and representative applications of ALD in fabricating high performance PEC electrodes with various nanostructures, including coating conformal thin films on three-dimensional scaffolds to facilitate the separation and migration of photocarriers and enhance light trapping.
Abstract: Photoelectrochemical (PEC) water splitting is an attractive approach to generate hydrogen as a clean chemical fuel from solar energy. But there remain many fundamental issues to be solved, including inadequate photon absorption, short carrier diffusion length, surface recombination, vulnerability to photo-corrosion, and unfavorable reaction kinetics. Owing to its self-limiting surface reaction mechanism, atomic layer deposition (ALD) is capable of depositing thin films in a highly controllable manner, which makes it an enabling technique to overcome some of the key challenges confronted by PEC water splitting. This tutorial review describes some unique and representative applications of ALD in fabricating high performance PEC electrodes with various nanostructures, including (i) coating conformal thin films on three-dimensional scaffolds to facilitate the separation and migration of photocarriers and enhance light trapping, as well as realizing controllable doping for bandgap engineering and forming homojunctions for carrier separation; (ii) achieving surface modification through deposition of anti-corrosion layers, surface state passivation layers, and surface catalytic layers; and (iii) identifying the main rate limiting steps with model electrodes with highly defined thickness, composition, and interfacial structure.
TL;DR: In this paper, the effect of nanoscale pinholes in compact TiO2 layers on the device performance was investigated, and it was shown that the ALD-based layer acts as an efficient hole-blocking layer in perovskite solar cells; it offers a large shunt resistance and enables a high power conversion efficiency.
Abstract: A uniform and pinhole-free hole-blocking layer is necessary for high-performance perovskite-based thin-film solar cells. In this study, we investigated the effect of nanoscale pinholes in compact TiO2 layers on the device performance. Surface morphology and film resistance studies show that TiO2 compact layers fabricated using atomic layer deposition (ALD) contain a much lower density of nanoscale pinholes than layers obtained by spin coating and spray pyrolysis methods. The ALD-based TiO2 layer acts as an efficient hole-blocking layer in perovskite solar cells; it offers a large shunt resistance and enables a high power conversion efficiency of 12.56%.
TL;DR: In this article, an ultrathin amorphous ZnO oxide coating was applied to LiNi 0.5 Co 0.2 Mn 0.3 O 2 with precise thickness control at atomic scale.
Patent•
19 Feb 2014TL;DR: In this article, a substrate in a reaction space is contacted with pulses of a silicon precursor and a dopant precursor, such that the silicon precursors and the precursor adsorb on the substrate surface.
Abstract: The present disclosure relates to the deposition of dopant films, such as doped silicon oxide films, by atomic layer deposition processes. In some embodiments, a substrate in a reaction space is contacted with pulses of a silicon precursor and a dopant precursor, such that the silicon precursor and dopant precursor adsorb on the substrate surface. Oxygen plasma is used to convert the adsorbed silicon precursor and dopant precursor to doped silicon oxide.
TL;DR: In this paper, two types of pinholes in the blocking layers are classified, and their effective area is quantified, and frequency-independent Mott-Schottky plots are fitted from electrochemical impedance spectroscopy.
Abstract: Thin compact layers of TiO2 are grown by thermal oxidation of Ti, by spray pyrolysis, by electrochemical deposition, and by atomic layer deposition. These layers are used in dye-sensitized solar cells to prevent recombination of electrons from the substrate (FTO or Ti) with the hole-conducting medium at this interface. The quality of blocking is evaluated electrochemically by methylviologen, ferro/ferricyanide, and spiro-OMeTAD as the model redox probes. Two types of pinholes in the blocking layers are classified, and their effective area is quantified. Frequency-independent Mott–Schottky plots are fitted from electrochemical impedance spectroscopy. Certain films of the thicknesses of several nanometers allow distinguishing the depletion layer formation both in the TiO2 film and in the FTO substrate underneath the titania film. The excellent blocking function of thermally oxidized Ti, electrodeposited film (60 nm), and atomic-layer-deposited films (>6 nm) is documented by the relative pinhole area of less...
TL;DR: This work highlights a general approach to improve the performance and stability of Si photoelectrodes by engineering the catalyst/semiconductor interface by incorporatingasma-enhanced atomic layer deposition of cobalt oxide onto nanotextured p(+)n-Si devices.
Abstract: Plasma-enhanced atomic layer deposition of cobalt oxide onto nanotextured p+n-Si devices enables efficient photoelectrochemical water oxidation and effective protection of Si from corrosion at high pH (pH 13.6). A photocurrent density of 17 mA/cm2 at 1.23 V vs RHE, saturation current density of 30 mA/cm2, and photovoltage greater than 600 mV were achieved under simulated solar illumination. Sustained photoelectrochemical water oxidation was observed with no detectable degradation after 24 h. Enhanced performance of the nanotextured structure, compared to planar Si, is attributed to a reduced silicon oxide thickness that provides more intimate interfacial contact between the light absorber and catalyst. This work highlights a general approach to improve the performance and stability of Si photoelectrodes by engineering the catalyst/semiconductor interface.
TL;DR: It is found that unlike chalcogen-enriched NC surfaces that are structurally, optically, and electronically unstable, lead chloride treatment creates a well-passivated shell that stabilizes the NCs.
Abstract: We report a simple, solution-based, postsynthetic colloidal, atomic layer deposition (PS-cALD) process to engineer stepwise the surface stoichiometry and therefore the electronic properties of lead chalcogenide nanocrystal (NC) thin films integrated in devices. We found that unlike chalcogen-enriched NC surfaces that are structurally, optically, and electronically unstable, lead chloride treatment creates a well-passivated shell that stabilizes the NCs. Using PS-cALD of lead chalcogenide NC thin films we demonstrate high electron field-effect mobilities of ∼4.5 cm2/(V s).
TL;DR: In situ transmission electron microscopy unveiled the dynamic mechanical protection of the ALD-Al2O3 coating by coherently deforming with the SnNPs under the huge volume changes during charging/discharging, a key to improving battery cycle performance.
Abstract: Atomic-layer-deposition (ALD) coatings have been increasingly used to improve battery performance. However, the electrochemical and mechanistic roles remain largely unclear, especially for ALD coatings on electrodes that undergo significant volume changes (up to 100%) during charging/discharging. Here we investigate an anode consisting of tin nanoparticles (SnNPs) with an ALD-Al2O3 coating. For the first time, in situ transmission electron microscopy unveiled the dynamic mechanical protection of the ALD-Al2O3 coating by coherently deforming with the SnNPs under the huge volume changes during charging/discharging. Battery tests in coin-cells further showed the ALD-Al2O3 coating remarkably boosts the cycling performance of the Sn anodes, comparing with those made of bare SnNPs. Chemomechanical simulations clearly revealed that a bare SnNP debonds and falls off the underlying substrate upon charging, and by contrast the ALD-Al2O3 coating, like ion-conductive nanoglue, robustly anchors the SnNP anode to the s...
TL;DR: In this paper, the degradation of ferroelectric properties of atomic layer deposited Hf0.5Zr 0.5O2 films with increasing thickness was mitigated by inserting 1'nm-thick Al2O3 interlayer at middle position of the thickness of the FE film.
Abstract: The degradation of ferroelectric (FE) properties of atomic layer deposited Hf0.5Zr0.5O2 films with increasing thickness was mitigated by inserting 1 nm-thick Al2O3 interlayer at middle position of the thickness of the FE film. The large Pr of 10 μC/cm2, which is 11 times larger than that of single layer Hf0.5Zr0.5O2 film with equivalent thickness, was achieved from the films as thick as 40 nm. The Al2O3 interlayer could interrupt the continual growth of Hf0.5Zr0.5O2 films, and the resulting decrease of grain size prevented the formation of non-ferroelectric monoclinic phase. The Al2O3 interlayer also largely decreased the leakage current of the Hf0.5Zr0.5O2 films.
TL;DR: A general strategy for synthesizing supported bimetallic nanoparticles by atomic layer deposition is reported, where monometallic nanoparticle formation is avoided by selectively growing the secondary metal on the primary metal nanoparticle but not on the support.
Abstract: Multi-metallic nanoparticles constitute a new class of materials offering the opportunity to tune the properties via the composition, atomic ordering and size. In particular, supported bimetallic nanoparticles have generated intense interest in catalysis and electrocatalysis. However, traditional synthesis methods often lack precise control, yielding a mixture of monometallic and bimetallic particles with various compositions. Here we report a general strategy for synthesizing supported bimetallic nanoparticles by atomic layer deposition, where monometallic nanoparticle formation is avoided by selectively growing the secondary metal on the primary metal nanoparticle but not on the support; meanwhile, the size, composition and structure of the bimetallic nanoparticles are precisely controlled by tailoring the precursor pulse sequence. Such exquisite control is clearly demonstrated through in situ Fourier transform infrared spectroscopy of CO chemisorption by mapping the gradual atomic-scale evolution in the surface composition, and further confirmed using aberration-corrected scanning transmission electron microscopy.
TL;DR: In this article, a new chemical approach for the selective atomic layer deposition of ultrathin layers of zirconium oxide (ZrO2) on copper patterned silicon surfaces was reported.
Abstract: The authors report a new chemical approach for the selective atomic layer deposition of ultrathin layers of zirconium oxide (ZrO2) on copper patterned silicon surfaces. Instead of using common atomic layer deposition (ALD) oxygen sources such as water, oxygen, or ozone, the authors use ethanol, which serves as oxygen source for the ALD on the silicon side and as effective reducing agent on the copper side, thereby selectively depositing ZrO2 film on the silicon surface of the substrate without any deposition on copper up to at least 70 ALD cycles. The resulting ZrO2 nanofilm is found to be an effective copper diffusion barrier at temperatures at least up to 700 °C.
TL;DR: The authors' Al2O3/TiO2 NL films were found to exhibit excellent water anticorrosion and low gas permeation and require only low-temperature processing (<100 °C) and organic thin film transistors with excellent air-stability were fabricated.
Abstract: Organic electronic devices require a passivation layer that protects the active layers from moisture and oxygen because most organic materials are very sensitive to such gases. Passivation films for the encapsulation of organic electronic devices need excellent stability and mechanical properties. Although Al2O3 films obtained with plasma enhanced atomic layer deposition (PEALD) have been tested as passivation layers because of their excellent gas barrier properties, amorphous Al2O3 films are significantly corroded by water. In this study, we examined the deformation of PEALD Al2O3 films when immersed in water and attempted to fabricate a corrosion-resistant passivation film by using a PEALD-based Al2O3/TiO2 nanolamination (NL) technique. Our Al2O3/TiO2 NL films were found to exhibit excellent water anticorrosion and low gas permeation and require only low-temperature processing (<100 °C). Organic thin film transistors with excellent air-stability (52 days under high humidity (a relative humidity of 90% a...
TL;DR: A high-quality Sb₂S₃ thin-absorber with controllable thickness was reproducibly formed by atomic layer deposition (ALD) technique and is attributed to reduced backward recombination because of the inhibition of oxide defects within ALD-Sb⁂S ₃ absorber and the conformal deposition of very uniform absorbers on the blocking TiO₁ surface by ALD process.
Abstract: A high-quality Sb2S3 thin-absorber with controllable thickness was reproducibly formed by atomic layer deposition (ALD) technique. Compared with conventional chemical bath deposition (CBD), the Sb2S3 absorber deposited by ALD did not contain oxide or oxygen impurities and showed a very uniform thickness of Sb2S3 absorbers formed on a rough surface of dense blocking TiO2/F-doped SnO2 (bl-TiO2/FTO) substrate. The planar ALD-Sb2S3 solar cells comprised of Au/Poly-3-hexylthiophene/ALD-Sb2S3/bl-TiO2/FTO showed significantly improved power conversion efficiency of 5.77% at 1 sun condition and narrow efficiency deviation, whereas the planar CBD-Sb2S3 solar cells exhibited 2.17% power conversion efficiency. The high efficiency and good reproducibility of ALD-Sb2S3 solar cell devices is attributed to reduced backward recombination because of the inhibition of oxide defects within ALD-Sb2S3 absorber and the conformal deposition of very uniform Sb2S3 absorbers on the blocking TiO2 surface by ALD process.