Atmospheric Pressure Spatial Atomic Layer Research Articles

Compositionally engineered amorphous InZnO thin-film transistor with high mobility and stability via atmospheric pressure spatial atomic layer deposition

Amorphous indium-zinc oxide (IZO) thin films, featuring indium atomic concentrations between 35.2 and 64.2 at.%, were fabricated using atmospheric pressure spatial atomic layer deposition (AP S-ALD) at 250 °C, employing trimethylindium (TMI) and diethylzinc (DEZ) as precursors and ozone as the reactant, based on the atomic layer processing. The crystallinity and chemical bonding states of the IZO films were found to vary with the metal cation composition, as confirmed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). We fabricated thin-film transistors (TFTs) employing the IZO films as the active layer on polyimide (PI) substrates, achieving high mobility (45.7 cm2/V·s), excellent bias-temperature stress (BTS) stability (ΔVTH = 0.63 V), and maintaining stable electrical properties even after mechanical bending tests along two different axes. This study highlights the successful development of high-performance flexible devices by precisely controlling the metal cation composition using AP S-ALD based on high deposition rate.

High mobility and productivity of flexible In2O3 thin-film transistors on polyimide substrates via atmospheric pressure spatial atomic layer deposition

We fabricate In2O3 films using atmospheric pressure spatial atomic layer deposition (AP S-ALD) and investigate their properties at various temperatures (150 °C–225 °C). As the temperature increased, the growth per cycle (GPC) increases, with the GPC and refractive index reaching values of 1.33 and 2.02, respectively, at 225 °C. The In2O3 thin film indicates a reduction in carrier concentration from 1.53 ± 1.37 × 1021 to 3.09 ± 0.53 × 1020 cm−3 as the temperature increased, and a decrease in the resistance from 3.55 ± 0.07 × 10−3 to 3.70 ± 0.01 × 10−4 Ω∙cm, which is attributed to a decrease in the impurity concentration (150 °C: 1.5 at.%; 175 °C: 1.0 at.%; 200 °C: N/A; 225 °C: N/A) and an increase in crystallinity. We use the In2O3 film as a channel layer in a top-gate bottom-contact thin-film transistor (TG-BC TFT). The device shows excellent performance characteristics, including a field-effect mobility of 69.8 cm2/V·s, a threshold voltage of −0.06 ± 0.22 V, and a subthreshold swing of 0.16 ± 0.01 V/decade. We successfully fabricated high-mobility TFTs and demonstrated their reliability via bias and 50,000 bending tests. The high-performance channel layer of the TFTs fabricated using AP S-ALD are promising for flexible applications.

Highly Transparent and Stable Flexible Electrodes Based on MgO/AgNW Nanocomposites for Transparent Heating Applications

AbstractTransparent electrodes (TE) based on silver nanowire (AgNW) exhibit good physical properties and constitute a promising alternative to transparent conductive oxides due to their low cost, flexibility, and low toxicity. Nevertheless, they suffer from stability issues over harsh conditions, and encapsulation allows to overcome these limitations. Herein, the low‐cost, scalable fabrication and study of transparent electrodes based on sprayed AgNW networks coated with MgO thin films deposited by atmospheric pressure spatial atomic layer deposition (AP‐SALD) at mild deposition temperature (≤220 °C) is reported. Fabrication of MgO thin films by AP‐SALD is reported here for the first time, and their deposition on different substrates is optimized. MgO exhibits a pure phase and conformal growth with a preferential (220) crystalline orientation and a higher growth rate as compared to conventional atomic layer deposition (ALD). Furthermore, thanks to the conformal coating of MgO on AgNW, the obtained nanocomposites exhibit great optical transparency of ≈85% and flexibility while maintaining high stability under thermal and electrical stress. Indeed, this study shows a clear enhancement of the stability of AgNW networks for thin MgO coatings of only a few nanometers thick. Finally, a proof‐of‐concept transparent heater is fabricated to melt a piece of cheese.

Impact of air exposure on growth rate and electrical properties of SnO2 thin films by atmospheric pressure spatial atomic layer deposition

SnO2 thin film is one of the most studied transparent conductive materials that can be deposited using vacuum-free techniques such as atmospheric pressure spatial atomic layer deposition (AP-SALD). This work studies SnO2 thin films prepared from tin(II) acetylacetonate and water vapor, with a particular focus on the impact of air exposure during the AP-SALD process on the growth rate and electrical properties of the films. In-situ resistance measurements and ex-situ Hall effect characterization demonstrated that longer exposure time of the growing film surface to the open air (t air) at 240 °C led to conductivity degradation, while the film thickness decreases. The theoretical calculations show that −OH and (oxygen molecule adsorbed on the five-coordinated Sn atom, also called O2 dimer) are the two most stable surface structures. The formation of is shown as the most thermodynamically favorable oxygen-related species on SnO2(110) surface formed when the film is exposed to the open air, giving rise to both the decrease of film thickness (associated with the desorption of −OH surface groups) and the increase of film resistivity versus t air. The optimized polycrystalline SnO2 sample demonstrated relatively good electrical performance, including an electrical resistivity of 9.3 × 10−3 Ω.cm, carrier density of 9.2 × 1019 cm−3, and Hall mobility of 7.3 cm2 V−1 s−1 at a growth temperature as low as 240 °C. Our findings reveal the critical impact of processing in the open air on the electrical conductivity of the obtained SnO2 films by AP-SALD coating technology.

Silver nanowire electrodes for transparent light emitting devices based on WS2 monolayers

Transition metal dichalcogenide (TMDC) monolayers with their direct band gap in the visible to near-infrared spectral range have emerged over the past years as highly promising semiconducting materials for optoelectronic applications. Progress in scalable fabrication methods for TMDCs like metal-organic chemical vapor deposition (MOCVD) and the ambition to exploit specific material properties, such as mechanical flexibility or high transparency, highlight the importance of suitable device concepts and processing techniques. In this work, we make use of the high transparency of TMDC monolayers to fabricate transparent light-emitting devices (LEDs). MOCVD-grown WS2 is embedded as the active material in a scalable vertical device architecture and combined with a silver nanowire (AgNW) network as a transparent top electrode. The AgNW network was deposited onto the device by a spin-coating process, providing contacts with a sheet resistance below 10 Ω sq−1 and a transmittance of nearly 80%. As an electron transport layer we employed a continuous 40 nm thick zinc oxide (ZnO) layer, which was grown by atmospheric pressure spatial atomic layer deposition (AP-SALD), a precise tool for scalable deposition of oxides with defined thickness. With this, LEDs with an average transmittance over 60% in the visible spectral range, emissive areas of several mm2 and a turn-on voltage of around 3 V are obtained.

Selective spatial atomic layer deposition of Cu, Cu2O, and CuO thin films in the open air: reality or fiction?

Copper and binary copper oxide thin films are key materials for microelectronic, optoelectronic, and sensing devices. Herein, we report innovative atmospheric pressure spatial atomic layer deposition processes enabling the facile control over the copper oxidation state. The selective deposition of Cu, Cu2O, and CuO thin films at low temperatures (160–260 °C) has been achieved by using Cu(I)(hfac)(tmvs) as copper source and nitrogen, water, or ozone as coreactants, respectively. The three obtained materials are pure and crystalline, as revealed by X-ray absorption spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. The deposition mechanism of the Cu, Cu2O, and CuO phases is based on disproportionation, hydrolysis, and oxidation reactions. Interestingly, metallic copper films with resistivity as low as ∼3.7 × 10−6 Ω·cm have been obtained, and resistivity values of 100 Ω·cm and 0.2 Ω·cm have been measured for the Cu2O and CuO semiconductor layers, respectively. Although working in an open-air environment, the oxidation state of copper-based thin films can be controlled using the same precursor, thus reducing cross-contamination and allowing for a faster and more reliable process. This demonstrates the versatility of atmospheric-pressure spatial atomic layer deposition and opens prospects for the manufacturing of novel devices such as wearables, sensors, or flexible electronics.

Controlled Crystallinity of TiO2 Layers Grown by Atmospheric Pressure Spatial Atomic Layer Deposition and their Impact on Perovskite Solar Cell Efficiency

Atmospheric Pressure Spatial Atomic Layer Deposition (AP-SALD) is an upcoming deposition technique suitable for a variety of materials and combines the benefits of a regular atomic layer deposition with a significantly increased deposition rate at ambient conditions. In this work, amorphous and anatase TiO2 layers are fabricated by AP-SALD via systematic variation of process conditions such as temperature, reactant (H2O and O3), and posttreatment. The formed layers are characterized for their structural and optoelectronic properties and utilized as a hole-blocking layer in hybrid perovskite solar cells. It is found that TiO2 layers fabricated at elevated deposition temperatures possess strong anatase character but expose an unfavorable interface to the perovskite layer, promoting recombination and lowering the shunt resistance and open circuit voltage of the solar cells. Therefore, the interface is essential for efficient charge extraction, which can be significantly improved by controlling the process parameters.

Chemical deposition of Cu2O films with ultra-low resistivity: correlation with the defect landscape

Cuprous oxide (Cu2O) is a promising p-type semiconductor material for many applications. So far, the lowest resistivity values are obtained for films deposited by physical methods and/or at high temperatures (~1000 °C), limiting their mass integration. Here, Cu2O thin films with ultra-low resistivity values of 0.4 Ω.cm were deposited at only 260 °C by atmospheric pressure spatial atomic layer deposition, a scalable chemical approach. The carrier concentration (7.1014−2.1018 cm−3), mobility (1–86 cm2/V.s), and optical bandgap (2.2–2.48 eV) are easily tuned by adjusting the fraction of oxygen used during deposition. The properties of the films are correlated to the defect landscape, as revealed by a combination of techniques (positron annihilation spectroscopy (PAS), Raman spectroscopy and photoluminescence). Our results reveal the existence of large complex defects and the decrease of the overall defect concentration in the films with increasing oxygen fraction used during deposition.

ZIF-Based Metal-Organic Frameworks for Cantilever Gas Sensors

Among the different gas sensing platforms, cantilever-based sensors have attracted considerable interest in recent years thanks to their ultra-sensitivity and high-speed response. The gas sensing mechanism in a dynamic cantilever sensor is based on its resonance frequency shift upon adsorption of a gas molecule on the sensor. In order to sensitize the surface of a cantilever, a sensitive receptor material with large surface area is required. Metal-organic frameworks (MOFs) are a class of nanoporous crystalline materials composed of metal ions coordinated to organic linkers. MOFs are promising for gas sensing applications as they have large surface area, rich porosity with adjustable pore size and excellent selective adsorption capability for various gasses.[1] Zeolite imidazole frameworks (ZIFs) are a class of MOFs where metals with tetrahedral coordination (i.e. Zn, Co, Fe, Cu) are the central node and the ligands are imidazolate-based organic molecules.In this work, we developed a ZIF-based thin film for dynamic cantilever gas-sensing applications. We employed a novel atmospheric pressure spatial atomic layer deposition (AP-SALD)[2][3] technique to deposit a ZnO sacrificial layer on the silicon cantilevers. This technique allows the deposition of high-quality films at atmospheric pressure, faster than conventional ALD. The ZnO layer was then converted to a particular ZIF film with desired porosity and size, through a MOF-CVD process.[4] A gas-sensing bench setup was developed for the cantilever actuation and read-out. We present the chemical and morphological properties of the ZIF, as well as the frequency response of the sensor to various gases. The device showed reliable sensitivity to humidity, CO2 and several VOCs.

Atmospheric pressure spatial ALD of Al2O3 thin films for flexible PEALD IGZO TFT application

Atmospheric pressure spatial atomic layer deposition (AP S-ALD)-derived Al2O3 films were investigated on the growth temperatures (100 °C ∼ 200 °C) and demonstrated as the gate insulator for IGZO thin film transistor (TFT) applications. When the growth temperature increases to 200 °C, growth per cycle (GPC) and refractive index of the Al2O3 films were 1.33 Å/cycle and 1.63, respectively. The film density also increased from 2.55 g/cm3 to 2.79 g/cm3 on the growth temperature, which decreasing the carbon impurities of the Al2O3 film (100 °C: 3.57 at%, 150 °C: 1.73 at%, 200 °C: N/A). In addition, the impurity and low growth temperature may degrade not only film surface roughness, but also electrical characteristics. As the buffer and gate insulator Al2O3 layers, the IGZO TFT were fabricated on a polyimide substrate. The IGZO TFTs with the Al2O3 layers showed excellent device performances: 52.48 cm2/V.sec of field effect mobility, −3.09 ± 0.14 of threshold voltage, and 0.14 ± 0.01 subthreshold swing. In addition, the TFT exhibited excellent bias reliability and mechanical bending stability. This highly stability will be attributed to AP S-ALD Al2O3 acting as an excellent insulator.

Silver Nanowire Networks: Ways to Enhance Their Physical Properties and Stability.

Silver nanowire (AgNW) networks have been intensively investigated in recent years. Thanks to their attractive physical properties in terms of optical transparency and electrical conductivity, as well as their mechanical performance, AgNW networks are promising transparent electrodes (TE) for several devices, such as solar cells, transparent heaters, touch screens or light-emitting devices. However, morphological instabilities, low adhesion to the substrate, surface roughness and ageing issues may limit their broader use and need to be tackled for a successful performance and long working lifetime. The aim of the present work is to highlight efficient strategies to optimize the physical properties of AgNW networks. In order to situate our work in relation to existing literature, we briefly reported recent studies which investigated physical properties of AgNW networks. First, we investigated the optimization of optical transparency and electrical conductivity by comparing two types of AgNWs with different morphologies, including PVP layer and AgNW dimensions. In addition, their response to thermal treatment was deeply investigated. Then, zinc oxide (ZnO) and tin oxide (SnO2) protective films deposited by Atmospheric Pressure Spatial Atomic Layer Deposition (AP-SALD) were compared for one type of AgNW. We clearly demonstrated that coating AgNW networks with these thin oxide layers is an efficient approach to enhance the morphological stability of AgNWs when subjected to thermal stress. Finally, we discussed the main future challenges linked with AgNW networks optimization processes.

Nanoscale Film Thickness Gradients Printed in Open Air by Spatially Varying Chemical Vapor Deposition

Nanoscale films are integral to all modern electronics. To optimize device performance, researchers vary the film thickness by making batches of devices, which is time-consuming and produces experimental artifacts. We present thin films with nanoscale thickness gradients that are rapidly deposited in open air for combinatorial and high-throughput (CHT) studies. Atmospheric pressure spatial atomic layer deposition reactor heads are used to produce spatially varying chemical vapor deposition rates on the order of angstroms per second. We printed ZnO and Al2O3 films with nm-scale thickness gradients in as little as 45 seconds and performed CHT analysis of a MIM diode and perovskite solar cell. By testing 360 Pt/Al2O3/Al diodes with 18 different Al2O3 thicknesses on a single substrate, we identified a thicker insulator layer (6.5 to 7.0 nm) for optimal diode performance than has been reported previously. An Al2O3 thin film encapsulation layer was deposited by atmospheric pressure chemical vapor deposition (AP-CVD) on a perovskite solar cell stack for the first time and a convolutional neural network was developed to analyze the perovskite stability. The rapid nature of AP-CVD enables thicker films to be deposited at a higher temperature than is practical with conventional atomic layer deposition. The CHT analysis showed enhanced stability for 70 nm encapsulation films.

Nanoscale Film Thickness Gradients Printed in Open Air by Spatially Varying Chemical Vapor Deposition

AbstractNanoscale films are integral to all modern electronics. To optimize device performance, researchers vary the film thickness by making batches of devices, which is time‐consuming and produces experimental artifacts. Thin films with nanoscale thickness gradients that are rapidly deposited in open air for combinatorial and high‐throughput (CHT) studies are presented. Atmospheric pressure spatial atomic layer deposition reactor heads are used to produce spatially varying chemical vapor deposition rates on the order of angstroms per second. ZnO and Al2O3 films are printed with nm‐scale thickness gradients in as little as 45 s and CHT analysis of a metal‐insulator‐metal diode and perovskite solar cell is performed. By testing 360 Pt/Al2O3/Al diodes with 18 different Al2O3 thicknesses on one wafer, a thicker insulator layer (≈7.0 nm) is identified for optimal diode performance than reported previously. Al2O3 thin film encapsulation is deposited by atmospheric pressure chemical vapor deposition (AP‐CVD) on a perovskite solar cell stack for the first time and a convolutional neural network is developed to analyze the perovskite stability. The rapid nature of AP‐CVD enables thicker films to be deposited at a higher temperature than is practical with conventional methods. The CHT analysis shows enhanced stability for 70 nm encapsulation films.

In-situ observation of nucleation and property evolution in films grown with an atmospheric pressure spatial atomic layer deposition system

Atmospheric pressure—spatial atomic layer deposition (AP-SALD) is a promising open-air deposition technique for high-throughput manufacturing of nanoscale films, yet the nucleation and property evolution in these films has not been studied in detail. In this work, in situ reflectance spectroscopy was implemented in an AP-SALD system to measure the properties of Zinc oxide (ZnO) and Aluminum oxide (Al2O3) films during their deposition. For the first time, this revealed a substrate nucleation period for this technique, where the length of the nucleation time was sensitive to the deposition parameters. The in situ characterization of thickness showed that varying the deposition parameters can achieve a wide range of growth rates (0.1–3 nm/cycle), and the evolution of optical properties throughout film growth was observed. For ZnO, the initial bandgap increased when deposited at lower temperatures and subsequently decreased as the film thickness increased. Similarly, for Al2O3 the refractive index was lower for films deposited at a lower temperature and subsequently increased as the film thickness increased. Notably, where other implementations of reflectance spectroscopy require previous knowledge of the film’s optical properties to fit the spectra to optical dispersion models, the approach developed here utilizes a large range of initial guesses that are inputted into a Levenberg-Marquardt fitting algorithm in parallel to accurately determine both the film thickness and complex refractive index.

Fast-Charging All-Solid-State 3D Li-Ion Battery with Ultra-Thin Lipon and High-Capacity Electrodes Using Large-Area Atmospheric-Pressure Spatial ALD

The key challenges in next-generation all-solid-state Li-ion battery technology are related to the energy and power densities required, fast charging constraints, battery lifetime, while keeping the cost low by high-volume manufacturing. Currently, EVs are based on Li-ion batteries that often utilize highly flammable and toxic components such as liquid organic electrolyte, thus imposing a potential threat in case of failure. There is high pressure on developing batteries that are safer, smaller, and cheaper. Here, we report on innovative materials and architectural approaches that have the potential to disrupt current Li-ion battery technology, especially by combining high-capacity with high charging/discharging rates. We aimed at improving 3D battery performance by using large area atmospheric pressure spatial atomic layer deposition (sALD) for further tuning the electrode and electrolyte layers at the nanometer-scale. Apart from enabling high charge/discharge rates, 3D electrode architectures pave the way for the use of high-capacity materials without long-term cycling challenges. We will show the potential of the intrinsically safe 3D all-solid-state batteries that can be extended to energy densities required for automotive (850 Wh/l and 375 Wh/kg at cell level). However, novel architectures demand newer processing techniques, especially for conformal layer stacks over 3D structures. In this regard, we will present the results on high-rate 3D Li-ion battery electrodes coated using our patented sALD technology, which enables charging times below 10 minutes. Next, we will discuss the first-ever sALD-based LiPON electrolyte material, deposited at least 10x faster than the current technologies using conventional ALD systems, and exhibiting high Li-ion conductivity > 10-7 S/cm and very low electronic conductivity (< 10-12 S/cm). The LiPON layers are pinhole-free and demonstrated to be cycled without shorts. Such electrolytes are also relevant for the development of protection layers in wet electrolyte-based lithium ion batteries, as well as for enabling thin-film planar and 3D solid-state batteries with ultrathin electrolyte layers (few 10’s of nanometers). Highlighted during the presentation will also be the attribute of the sALD technique to produce conformal and upscalable coatings that can be applied in roll-to-roll processing using metal foils to further enable the innovative and cost-effective 3D battery layers.

Low-cost fabrication of flexible transparent electrodes based on Al doped ZnO and silver nanowire nanocomposites: impact of the network density.

We report the study of nanocomposite transparent electrodes based on aluminium doped zinc oxide (ZnO : Al) thin films and silver nanowire (AgNW) networks. The electrodes are fully fabricated by low-cost, open-air techniques, namely, atmospheric pressure spatial atomic layer deposition and spray coating. We show that the transparency and the electrical conductivity of the ZnO : Al/AgNW nanocomposites can be tuned by controlling the AgNW network density. We also demonstrate that the thermal, electrical and mechanical stabilities of the nanocomposites are drastically enhanced compared to those of AgNW networks or ZnO : Al thin films separately. Interestingly, we report a clear continuous decrease of the electrical resistance of the nanocomposites for network densities even below the percolation threshold. We propose a model to explain the relationship between the conductivity of the nanocomposites and the AgNW network density. Our physical model is based on the non-negligible contribution of percolating clusters of AgNWs for network densities below the percolation threshold. Our results provide a means to predicting the physical properties of such nanocomposites for applications in solar cells and other optoelectronic devices. Finally, the deposition methods used open the way towards stable, low-cost and flexible transparent electrodes for industrial applications.

The Role of Humidity in Tuning the Texture and Electrical Properties of Cu2O Thin Films Deposited via Aerosol‐Assisted CVD

AbstractA study on the effect of carrier gas (CG) humidity on the texture and the resulting electronic properties of Cu2O thin films deposited using aerosol‐assisted chemical vapor deposition (AA‐CVD) at low temperatures (&lt;365 °C) is reported. By increasing the CG humidity, the preferred orientation of the films can be tuned from [110] to [111]. By studying the initial stages of film deposition, a different growth mode is found for dry and humid conditions, which in turn directs the final texture of the films. The analysis of the electric properties of the films by Hall effect shows that carrier concentration remains in the order of 1015 cm−3 when using both dry and humid conditions. Converselly, Cu2O samples deposited with humid CG generally present a higher mobility, up to 17 cm2 V−1 s−1. [111]‐textured Cu2O films with high mobility were used to fabricate a diode by depositing a ZnO layer on top using atmospheric pressure spatial atomic layer deposition (AP‐SALD). The diode shows an excellent rectifying behavior with a high asymmetry close to 104 between −1 and +1 V.

Highly Efficient and Stable Semi‐Transparent p‐i‐n Planar Perovskite Solar Cells by Atmospheric Pressure Spatial Atomic Layer Deposited ZnO

The replacement of the conventional top metal contact with a semi‐transparent conducting electrode such as sputtered indium‐tin oxide (ITO) is strictly required to adopt the perovskite solar cell (PSC) in hybrid tandem photovoltaic applications. In order to prevent sputtering damages on the perovskite absorber and the organic materials adopted in p‐i‐n planar architecture, an atmospheric pressure spatial atomic layer deposited (s‐ALD) ZnO buffer layer has been included. The use of a 45 nm thick s‐ALD layer enables the fabrication of a PSC with a power conversion efficiency (PCE) of 14.7%, with a similar PCE when illuminated from the ITO/s‐ALD ZnO side. When adopted in a four terminal configuration with a c‐Si solar cell (PCE of 18.6%), a 2.5% absolute PCE gain is observed with respect to the stand alone c‐Si. Finally, the semi‐transparent PSC shows an excellent shelf life, and only −4% degradation on the tracked maximum power point when encapsulated and aged at 65 °C in an inert atmosphere after 1500 h.

Stability Enhancement of Silver Nanowire Networks with Conformal ZnO Coatings Deposited by Atmospheric Pressure Spatial Atomic Layer Deposition.

Silver nanowire (AgNW) networks offer excellent electrical and optical properties and have emerged as one of the most attractive alternatives to transparent conductive oxides to be used in flexible optoelectronic applications. However, AgNW networks still suffer from chemical, thermal, and electrical instabilities, which in some cases can hinder their efficient integration as transparent electrodes in devices such as solar cells, transparent heaters, touch screens, and organic light emitting diodes. We have used atmospheric pressure spatial atomic layer deposition (AP-SALD) to fabricate hybrid transparent electrode materials in which the AgNW network is protected by a conformal thin layer of zinc oxide. The choice of AP-SALD allows us to maintain the low-cost and scalable processing of AgNW-based transparent electrodes. The effects of the ZnO coating thickness on the physical properties of AgNW networks are presented. The composite electrodes show a drastic enhancement of both thermal and electrical stabilities. We found that bare AgNWs were stable only up to 300 °C when subjected to thermal ramps, whereas the ZnO coating improved the stability up to 500 °C. Similarly, ZnO-coated AgNWs exhibited an increase of 100% in electrical stability with respect to bare networks, withstanding up to 18 V. A simple physical model shows that the origin of the stability improvement is the result of hindered silver atomic diffusion thanks to the presence of the thin oxide layer and the quality of the interfaces of hybrid electrodes. The effects of ZnO coating on both the network adhesion and optical transparency are also discussed. Finally, we show that the AP-SALD ZnO-coated AgNW networks can be effectively used as very stable transparent heaters.

Oxidation of copper nanowire based transparent electrodes in ambient conditions and their stabilization by encapsulation: application to transparent film heaters

Whereas the integration of silver nanowires in functional devices has reached a fair level of maturity, the integration of copper nanowires still remains difficult, mainly due to the intrinsic instability of copper nanowires in ambient conditions. In this paper, copper nanowire based transparent electrodes with good performances (33 Ω sq−1 associated with 88% transparency) were obtained, and their degradation in different conditions was monitored, in particular by electrical measurements, transmission electron microscopy, x-ray photoelectron spectrometry and Auger electron spectroscopy. Several routes to stabilize the random networks of copper nanowires were evaluated. Encapsulation through laminated barrier film with optical clear adhesive and atmospheric pressure spatial atomic layer deposition were found to be efficient and were used for the fabrication of transparent film heaters.