Thick Indium Tin Oxide Layer Research Articles

Real-Time ITO Layer Thickness for Solar Cells Using Deep Learning and Optical Interference Phenomena

The thickness of the indium tin oxide (ITO) layer is a critical parameter affecting the performance of solar cells. Traditional measurement methods require sample collection, leading to manufacturing interruptions and potential quality issues. In this paper, we propose a real-time, non-contact approach using deep learning and optical interference phenomena to estimate the thickness of ITO layers in solar cells. We develop a convolutional neural network (CNN) model that processes microscopic images of solar cells and predicts the ITO layer thickness. In addition, mean absolute error (MAE) and mean squared error (MSE) loss functions are combined to train the model. Experimental results demonstrate the effectiveness of our approach in accurately estimating the ITO layer thickness. The integration of computer vision and deep learning techniques provides a valuable tool for non-destructive testing and quality control in the manufacturing of solar cells. The loss of the model after training is reduced to 0.83, and the slope of the test value in the scatter plot with the true value of the ellipsometer is approximately equal to 1, indicating the high reliability of the model.

Multifunctional Titanium Oxide Layers in Silicon Heterojunction Solar Cells Formed via Selective Anodization

Herein, a novel strategy is introduced to reduce the consumption of scarce materials in silicon heterojunction solar cells by combining approaches for Ag replacement in the metallization and a reduction of the indium tin oxide layer thickness: a Ti layer deposited by physical vapor deposition serves both as the contact layer of a copper‐based metallization and after electrochemical oxidation as capping layer enabling the use of a thinner transparent conductive oxide. Further, the TiOx layer can build an encapsulation layer. While oxygen evolution and metal dissolution are found to be critical side reactions, a nonaqueous electrolyte is found in which these reactions can be avoided. The application on silicon heterojunction solar cells shows promising first results, exhibiting a short circuit current density of 35 mA cm−2 and a cell efficiency of close to 21% despite nonoptimized layer thicknesses.

Influence of Post Processing on Thermal Conductivity of ITO Thin Films

This work presents the influence of post processing on morphology, thermal and electrical properties of indium tin oxide (ITO) thin films annealed at 400 °C in different atmospheres. The commercially available 170 nm thick ITO layers deposited on glass were used as a starting material. The X-ray diffraction measurements revealed polycrystalline structure with dominant signal from (222) plane for all samples. The annealing reduces the intensity of this peak and causes increase of (221) and (440) peaks. Atomic force microscopy images showed that the surface morphology is typical for polycrystalline layers with roughness not exceeding few nm. Annealing in the oxygen and the nitrogen-hydrogen mixture (NHM) changes shapes of grains. The electrical conductivity decreases after annealing except the one of layer annealed in NHM. Thermal conductivities of annealed ITO thin films were in range from 6.4 to 10.6 W·m-1·K-1, and they were higher than the one for starting material-5.1 W·m-1·K-1. Present work showed that annealing can be used to modify properties of ITO layers to make them useful for specific applications e.g., in ITO based solar cells.

Determination of layer morphology of rough layers in organic light emitting diodes by X‐ray reflectivity

AbstractX‐ray reflectivity (XRR) has been proven to be a useful tool to investigate thin layers as well as buried interfaces in stacks built of very thin layers. Nevertheless, x‐ray reflectivity measurements are limited by the roughness of the layers and interfaces as the roughness destroys the interference structure, the so‐called Kiessig fringes. As investigations of thin layers in organic light emitting devices (OLEDs) are still subject of research and development, the focus of this paper is the investigation of a layer of indium tin oxide (ITO) which serves as transparent anode material in OLEDs. Due to the fabrication process, ITO shows rough surface structures, so‐called spikes, hindering the determination of the ITO layer thickness and roughness in XRR measurements. In this paper, it is theoretically and experimentally proven that a smoothing layer on the ITO enables the determination of the buried ITO layer thickness and roughness as well as the density of the spikes. Furthermore, a sputtered aluminum layer (e.g. cathode material) showing spikes in atomic force microscopy covered with a smoothing layer reveals Kiessig fringes allowing the determination of the density of buried spikes. In general, it is shown that a smoothing layer on a rough surface enhances the sensitivity of x‐ray reflectivity measurements.

Holistic Approach toward a Damage-Less Sputtered Indium Tin Oxide Barrier Layer for High-Stability Inverted Perovskite Solar Cells and Modules.

The commercialization of perovskite solar cells (PSCs) requires the development of long-term, highly operational-stable devices. An efficient barrier layer plays a key role in improving the device stability of planar PSCs. Here, we focus on the use of sputtered indium tin oxide (ITO) as a barrier layer to stop major degradations. To mitigate efficiency losses of cells with the ITO barrier, we optimized various sputtering process parameters such as ITO layer thickness, target power density, and working pressure. The fabricated planar inverted PSCs based on the novel ITO barrier optimization demonstrate a power conversion efficiency (PCE) of 19.05% on a cell area of 0.09 cm2. The encapsulated cells retained >80% of their initial efficiency after 1400 h of continuous illumination at 55 °C and 94.5% of their initial PCE after 1500 h stored in air. Employing such a holistic stabilization approach, the PSC minimodules without encapsulation achieved an efficiency of 16.4% with a designated area of 2.28 cm2 and retained approximately 80% of the initial performance after thermal stress at 85 °C for 350 h under ambient conditions.

Design and Characterization of ITO-Covered Resonant Nanopillars for Dual Optical and Electrochemical Sensing

In this work we present a dual optical and electrochemical sensor based on SiO2/Si3N4 resonant nanopillars covered with an indium tin oxide (ITO) thin film. A 25–30 nm thick ITO layer deposited by magnetron sputtering acts as an electrode when incorporated onto the nanostructured array, without compromising the optical sensing capability of the nanopillars. Bulk sensing performances before and after ITO deposition have been measured and compared in accordance with theoretical calculations. The electrochemical activity has been determined by the ferri/ferrocyanide redox reaction, showing a remarkably higher activity than that of flat thin films of similar ITO nominal thickness, and proving that the nanopillar system covered by ITO presents electrical continuity. A label-free optical biological detection has been performed, where the presence of amyloid-β has been detected through an immunoassay enhanced with gold nanoparticles. Again, the experimental results have been corroborated by theoretical simulations. We have demonstrated that ITO can be a beneficial component for resonant nanopillars sensors by adding potential electrochemical sensing capabilities, without significantly altering their optical properties. We foresee that resonant nanopillars coated with a continuous ITO film could be used for simultaneous optical and electrochemical biosensing, improving the robustness of biomolecular identification.

Trapezium-shaped groove photonic crystal fiber plasmon sensor for low refractive index detection

A highly sensitive trapezium-shaped groove photonic crystal fiber (TSG-PCF) sensor based on surface plasmon resonance (SPR) is proposed and investigated numerically in low refractive index (RI) detection range of 1.181.30 by the finite element method (FEM). The trapezoidal groove is introduced, this sensor is simple in structure and manufactured easily. Indium tin oxide (ITO) is set as the sensing layer for the reaction between the core and the plasma. The influences of the structural parameters such as the holes parameters, the geometric parameters of the trapezium-shaped groove, the ITO layer thickness and other performance parameters on the design and sensing features of the proposed sensor are discussed comprehensively. The results show that for the proposed TSG-PCF, the maximum wavelength and amplitude sensitivities can arrive at 9100 nm/RIU and 99 RIU−1, the corresponding resolutions are 1.10 × 10−5 RIU and 1.01 × 10−4 RIU respectively in the analyte RI from 1.18 to 1.30. Moreover, the average sensitivity of 3429 nm/RIU can be realized for the appropriate parameters. The highly sensitive sensor makes the wide potential development for low RI detection in biological and chemical sensing.

GLAD Synthesized Silver Nanoparticle Patterned CeO2/ITO Vertical Junction UV Photodetector

This work presents the investigation of GLAD technique fabricated silver nanoparticles (Ag NPs) patterned cerium oxide (CeO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) nanorods on ITO (indium tin oxide) coated glass substrates for use as a UV photodetector. The fabricated samples were studied using numerous techniques such as XRD, FESEM along with EDS, UV-Visible absorption, PL and I-V characterization. The XRD pattern exhibited the polycrystalline nature of cubic fluorite CeO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> nanorod structure and ITO growing along (111) and (222) directions respectively. The average Ag NP size was found to be ~15.18 nm. FESEM image showed well patterning of Ag NPs on top of the vertically grown CeO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> nanorods with an average length of 440 nm on 200 nm thick ITO layer. UV-visible spectrum showed strong absorption in the UV region with the fabricated sample giving a direct bandgap of ~3.8 eV. PL spectrum showed a dominant emission at 379 nm due to transfer of charge from the Ce 4f band to the O 2p band. The device revealed good rectifying behavior giving a high photosensitivity of 2050.45 % and responsivity of 10.88 A/W at 4.8 V corresponding to 370 nm wavelength. Moreover, the figure of merits of photodetector such as detectivity, noise equivalent power (NEP) and external quantum efficiency (EQE%) were also investigated.

Extreme local field enhancement by hybrid epsilon-near-zero-plasmon mode in thin films of transparent conductive oxides.

Epsilon-near-zero (ENZ) materials display unique properties, and among them, large local field enhancement at ENZ frequency is of particular interest for many potential applications. In this Letter, we introduce the concept that a combination of epsilon-near-zero and surface plasmon polariton modes can be excited over an interface between a dielectric and a single ENZ layer in a specific frequency region, which can lead to extreme enhancement of local electric field. We demonstrate it with a systematic numerical simulation using finite element analysis and consider two configurations (Kretschmann configuration and a grating configuration), where an indium tin oxide (ITO) layer is sandwiched between two dielectric slabs. We confirm the formation of a hybrid mode at the ITO-dielectric interface at the wavelength of ENZ, as the ITO layer thickness reduces. The hybrid mode provides both high confinement and long propagation distance, which makes it more attractive for many applications than just a pure ENZ mode.

Improvement of carrier collection in Si/a-Si:H nanowire solar cells by using hybrid ITO/silver nanowires contacts

Optoelectronic devices based on high aspect ratio nanowires bring new challenges for transparent electrodes, which can be well addressed by using hybrid structures. Here we demonstrate that a composite contact to radial junction nanowire solar cells made of a thin indium-tin oxide (ITO) layer and silver nanowires greatly improves the collection of charge carriers as compared to a single thick ITO layer by reducing the series resistance losses while improving the transparency. The optimization is performed on p-i-n solar cells comprising of dense non-vertical nanowires with a p-doped c-Si core and an ultra-thin a-Si:H absorption layer grown by plasma-enhanced chemical vapor deposition on glass substrates. The optimal hybrid contact developed in this work is demonstrated to increase the solar cell conversion efficiency from 4.3% to 6.6%.

Impact of deposition of indium tin oxide double layers on hydrogenated amorphous silicon/crystalline silicon heterojunction

We report on the effect of sputtering deposition of indium tin oxide (ITO) as the transparent conductive oxide layer on the passivation performance of hydrogenated amorphous silicon/crystalline silicon heterojunctions. The influence of sputtering damage on passivation performance is studied by varying the ITO layer thickness from 0 nm to 80 nm. The passivation performance decreases considerably up to 10 nm and increases gradually from 20 nm to 80 nm, indicating that damage and recovery stages are present during the sputtering process. We focus on the injection energy as the cause of the recovery phenomenon. To optimize the passivation performance by intentionally enhancing the effect of the recovery stage while minimizing the initial damage at the heterointerface, we develop a two-step sputtering process in which the radiofrequency power is changed from 50 W to 100 W during deposition to prepare ITO double layers. Two step sputtering gives the lower damage, and the properties of ITO double layers are better than those of ITO single layers. These results show that two-step sputtering can realize greater a-Si:H passivation. Furthermore, better optical properties are obtained in ITO double layers compared with conventional ITO single layers. Therefore, modulating the radiofrequency power during ITO deposition can offer higher conversion efficiency.

Investigation of electrical values of low-efficiency dye-sensitized solar cells (DSSCs)

Indium-tin-oxide (ITO)/density (d)- titanium dioxide (TiO2)/nonporous (nonp)-TiO2 is a TiO2-based bilayer photoanode. These photoanodes coated for dye-sensitized solar cells (DSSCs) were with nonp-TiO2 surface and had very thick ITO layer. DSSCs were fabricated with these photoanodes. After their current density-voltage (J-V) were analyzed, ıt was seen that they were low efficiency and the shape of their J-V curve was linear line instead of rectangle. In this study, it was examined the relationship between the dark current (IDC), the series resistance (Rs) and the shunt resistance (Rsh) were examined for evaluating the fill factor (FF) of low-efficiency DSSCs because of the photoanodes with nonp-TiO2 surfaces and very thick ITO for contact layer. It was seen in the J-V graph of DSSCs which had low FF value due to their IDC and low Rsh. The J-V graph of low-efficiency DSSCs is linear due to their low Rsh and high Rs values. Moreover, the too thick ITO layer decreases the resistance of photoanodes; however, electrons in these photoanodes can not efficiently transferred to external circuit from ITO contact layer of DSSCs.

Magnetic Field Sensors Based on the Direct Magneto-Electric Effect in Hexaferrite Thin Films and the Equivalent Circuit Model

We propose the design, fabrication, experimental implementation, and equivalent circuit model of a magneto-electric (ME) sensing device for determining the magnitude and direction of low-frequency ac magnetic fields. The device consists of two capacitive ME thin-film sensors fabricated by means of the laser ablation technique inside a pulsed laser deposition (PLD) chamber. The films are grown on a 500-nm thick indium tin oxide layer on $1.5\times 1.5$ cm2 silicon substrates using two deposition methods, namely, single target (ST) and multiple target (MT). The proposed setup is used to detect ac magnetic fields generated from a solenoid coil located at a distance of 10 mm. The experimental results demonstrate that the proposed magnetic field sensing approach using the MT method can establish the magnitude and direction of external magnetic fields with detection errors below 8%. Based on the experimental observations, we also establish a mathematical expression describing the direct ME coupling effect observed in M-type strontium hexaferrite thin films. Subsequently, we develop an electrical circuit model that can accurately predict device behavior using circuit simulations. The differential output voltages at different field strengths are predicted for both ST and MT films by simulating this equivalent circuit using the LTspice software from Linear Technology. The simulation results are in good agreement with the experimental data both qualitatively and quantitatively, and the average difference between the two ranges from 5% to 19% in the worst case.

Coupling of Epsilon-Near-Zero Mode to Gap Plasmon Mode for Flat-Top Wideband Perfect Light Absorption

Epsilon-near-zero (ENZ) materials, when probed at or near wavelengths corresponding to their zero permittivity crossing points, have unique and interesting properties that can be exploited for enhancing nanoscale light–matter interactions. Here, we experimentally show that over an order of magnitude increase in the absorption band of a periodically patterned metal–dielectric–metal structure can be obtained by integrating an indium tin oxide (ITO) subwavelength nanolayer into the insulating dielectric gap region. Through incorporation of a 12 nm thick ITO layer between the patterned gold nanodisks and the SiO2 dielectric layer, a 240 nm wide, flat-top perfect (>98%) absorption centered at 1550 nm wavelength is enabled. The demonstrated wideband, perfect absorption resonance is shown to be due to coupling between the gap plasmon mode of the metasurface and the ENZ mode in the nanoscale ITO film.

Catalytic Electron Transfer at Nanoporous Indium Tin Oxide Electrodes

We investigated the enhancement of one electron transfer kinetics at the nanoporous indium tin oxide (ITO) electrodes. In this study, the origin of the catalytic activity in nanoporous electrodes was explored with regard to the effects of confined morphology of the electrode to the heterogeneous electron transfer enhancements. In order to look into the geometric contribution to electrocatalytic activity, we chose ITO as the electrode material due to its chemically inert surface on which most electron transfer reactions occur very slowly. Systematic variation of nanoporous ITO layer thickness allows us to effectively exclude the surface-originated electrocatalytic effects of the nanoporous electrodes such as defects. It was clearly found that the single electron transfer of Fe2+/3+ involving no proton transfer is more facilitated at thicker ITO nanoporous layers, which has longer pores, and this geometric enhancement was more evident at lower temperatures.

Low‐refractive‐index nanoparticle interlayers to reduce parasitic absorption in metallic rear reflectors of solar cells

Metal reflectors or electrodes in contact with optoelectronic devices can induce parasitic light absorption. A low‐refractive‐index (low‐n) layer inserted between the metal reflector and the optically active layer(s) reduces this absorption. We investigate the use of porous, nanoparticulate films as low‐n layers, and fabricate silicon solar cells with nanoparticle/silver rear reflectors. We vary the porosity and thus n (between 1.1 and 1.5) of the nanoparticle films, which are deposited by a controllable aerosol spray process, and investigate their effectiveness in reducing infrared parasitic absorption in the solar cells. Optical test structures incorporating films with the highest n exhibit an internal reflectance of over 99%, matching best‐in‐class structures; lower‐n layers should in theory perform better still but their rougher surfaces appear to induce plasmonic absorption in the overlying silver layer. No loss in open‐circuit voltage or fill factor is observed when applying the best nanoparticle films in silicon heterojunction solar cells, enabling efficiencies similar to those achieved with reference cells that employ a thick indium tin oxide layer between the wafer and the rear silver electrode.

Application of metal nanowire networks on hydrogenated amorphous silicon thin film solar cells

We demonstrate the application of metal nanowire (NW) networks as a transparent electrode on hydrogenated amorphous Si (a-Si:H) solar cells. We first systematically investigate the optical performances of the metal NW networks on a-Si:H solar cells in different electrode configurations through numerical simulations to fully understand the mechanisms to guide the experiments. The theoretically optimized configuration is discovered to be metal NWs sandwiched between a 40 nm indium tin oxide (ITO) layer and a 20 nm ITO layer. The overall performances of the solar cells integrated with the metal NW networks are experimentally studied. It has been found the experimentally best performing NW integrated solar cell deviates from the theoretically predicated design due to the performance degradation induced by the fabrication complicity. A 6.7% efficiency enhancement was achieved for the solar cell with metal NW network integrated on top of a 60 nm thick ITO layer compared to the cell with only the ITO layer due to enhanced electrical conductivity by the metal NW network.

Very thin ITO/metal mesh hybrid films for a high-performance transparent conductive layer in GaN-based light-emitting diodes

In this paper, we introduce very thin Indium tin oxide (ITO) layers (5, 10, and 15 nm) hybridized with a metal mesh to produce high-performance transparent conductive layers (TCLs) in near-ultraviolet light-emitting diodes (NUV LEDs). Using UV–vis–IR spectrometry, Hall measurement, and atomic force microscopy, we found that 10 nm was the optimal thickness for the very thin ITO layers in terms of outstanding transmittance and sheet resistance values as well as stable contact properties when hybridized with the metal mesh. The proposed layers showed a value of 4.56 Ω/□ for sheet resistance and a value of 89.1% for transmittance. Moreover, the NUV LEDs fabricated with the hybrid TCLs achieved ∼140% enhanced light output power compared to that of 150 nm thick ITO layers. Finally, to verify the practical usage of the TCLs for industrial applications, we packaged the NUV LED chips and obtained improved turn-on voltage (3.48 V) and light output power (∼116%) performance.

Ultralow Power Resistance Random Access Memory Device and Oxygen Accumulation Mechanism in an Indium–Tin-Oxide Electrode

This paper proposes low power consumption resistance random access memory (RRAM) devices with indium–tin-oxide (ITO) electrodes. The development of the Internet of Things (IoT) is a trend in future technology, but the bottleneck in IoT development is high power consumption; therefore, targeting low-power-consumption memory is crucial for the IoT. ITO-capped RRAM devices have been shown to exhibit outstanding performance and low power consumption, and here, we propose an oxygen accumulation mechanism by analyzing device characteristics. We find that the conduction current mechanism will be affected by oxygen absorbance in the ITO electrode. During the forming and set processes, oxygen ions will be propelled into the ITO electrode due to its oxygen vacancy-rich property; therefore, we find Schottky emission both at high-resistance state and low-resistance state and that the device exhibits an automatic current compliance property. Varied stop-voltage measurements were carried out to verify the device mechanism. Because of its capability for oxygen storage, the thick ITO layer was confirmed to affect the characteristic due to a difference in oxygen gradient. A new structure and novel material are proposed, based on the devices with ITO electrodes to improve performance and reduce power consumption.

Transparent Conductive ITO/Ag/ITO Electrode Deposited at Room Temperature for Organic Solar Cells

We investigated the optical and electrical properties of room-temperature-deposited indium-tin-oxide (ITO)/Ag (19 nm)/ITO multilayer films as a function of ITO layer thickness. The optical and electrical properties of the ITO/Ag/ITO films were compared with those of high-temperature-deposited ITO-only films for use as an anode in organic solar cells (OSCs). The ITO/Ag/ITO multilayer films had sheet resistances in the range 5.40–5.78 Ω/sq, while the ITO-only film showed 14.18 Ω/sq. The carrier concentration of the ITO/Ag/ITO films gradually decreased from 2.01 × 1022 to 7.20 × 1021 cm−3 as the ITO thickness increased from 17 nm to 83 nm. At 530 nm, the transmittance of the ITO/Ag/ITO (50 nm/19 nm/50 nm) films was ~90%, while that of the ITO-only film gave 96.5%. The multilayer film had a smooth surface with a root mean square (RMS) roughness of 0.49 nm. Poly (3-hexylthiophene) (P3HT):[6,6]-phenyl-C61 butyric acid methylester (PCBM) bulk heterojunction (BHJ)-based OSCs fabricated with the ITO/Ag/ITO (50 nm/19 nm/50 nm) film showed a power conversion efficiency (PCE) (2.84%) comparable to that of OSCs with a conventional ITO-only anode (3.48%).