Conductive Indium Tin Oxide Layer Research Articles

Inside the ovonic threshold switching (OTS) device based on GeSbSeN: Structural analysis under electrical and thermal stress

In this article, we present the structural investigation by Raman spectroscopy of GeSbSeN ovonic threshold switching (OTS) material once integrated in selector devices featuring a top electrode based on a transparent and conductive indium tin oxide layer. The devices are characterized by standard electrical protocols, and the structural evolution of the material is investigated after several switching operations. The results are correlated with the spectra obtained from blanket samples annealed at increasing temperature and are supported by XRD and TEM analyses. We establish a link between the evolution of the material structure with the annealing process and the device behavior along cycling, bringing important advancement in the understanding of the switching mechanism and of the origin of the failure in OTS devices.

An ultra-broadband and optically transparent metamaterial absorber based on multilayer indium-tin-oxide structure

In this work, an ultra-broadband and polarization-insensitive metamaterial absorber (MA) with high optical transparency is presented. Indium-tin-oxide (ITO) films are used as frequency selective surfaces in multiple conductive layers and also as the reflective backplane. Numerical simulation analysis demonstrates that the absorptivity of the proposed absorber exceeds 90% in the frequency range from 10 to 75.5 GHz, corresponding to a relative absorption bandwidth of 153%. The proposed structure has a total thickness of 2.9 mm, which is approximately 1/10 of the free space wavelength of its lowest operating frequency. The absorber also has good polarization insensitivity due to its symmetric geometry. Moreover, for TE-polarized waves, the proposed absorber can maintain an absorptivity greater than 70% for frequencies ranging from 10 to 80 GHz as the incident angle is increased to 45°. For TM-polarized waves, it provides absorptivity of more than 80% at incident angles up to 60°. Surface current distribution on each conductive ITO layer was simulated to analyze the absorption mechanism of the MA. A prototype composed of 16 × 16 unit cells was fabricated and the experimental results show a good agreement with the numerical simulations. Due to its ultra-wideband absorption and wide-incident-angle stability, the proposed MA has potential value in electromagnetic applications such as optically transparent EM shielding and microwave radiation protection.

Ultrathin channels make transistors go faster.

Reducing the thickness of an amorphous conductive indium tin oxide layer down to a few nanometres has enabled the realization of 40-nm-long channel transistors with remarkable operating characteristics.

Anti-reflective coating with a conductive indium tin oxide layer on flexible glass substrates.

Flexible glass has many applications including photovoltaics, organic light-emitting device (OLED) lighting, and displays. Its ability to be processed in a roll-to-roll facility enables high-throughput continuous manufacturing compared to conventional glass processing. For photovoltaic, OLED lighting, and display applications, transparent conductors are required with minimal optical reflection losses. Here, we demonstrate an anti-reflective coating (ARC) that incorporates a useful transparent conductor that is realizable on flexible substrates. This reduces the average reflectivity to less than 6% over the visible band from normal incidence to incident angles up to 60°. This ARC is designed by the average uniform algorithm method. The coating materials consist of a multilayer stack of an electrically functional conductive indium tin oxide with conductivity 2.95×105 Siemens/m (31Ω/□), and AlSiO2. The coatings showed modest changes in reflectivity and no delamination after 10,000 bending cycles. This demonstrates that effective conductive layers can be integrated into ARCs and can be realized on flexible glass substrates with proper design and process control.

Growth, surface treatment and characterization of polycrystalline lead iodide thick films prepared using close space deposition technique

Lead iodide (PbI2) polycrystalline thick films were fabricated on glass substrates with a conductive indium–tin-oxide layer using a close space deposition technique. The morphology of the as-deposited PbI2 films is typically and highly oriented polycrystalline structure, made up of microcrystal platelets upright on the substrate plane. Two techniques including the surface mechanical cutting and after-growth cadmium telluride coating were employed to improve the films′ surface properties. It was shown that both of the film surface treatment methods markedly decreased the dark current of PbI2 films. The photo-to-dark current ratio of about 2.05 under 241Am γ-ray source with activity of 2.78μCi irradiation was obtained from the film treated using both surface cutting and after-growth CdTe coating. Charge transport characteristics of these films were measured and the hole mobility 7.7×10−2–1.67×10−1cm2/Vs was estimated.

Amorphous silicon carbide heterojunction solar cells on p-type substrates

The performance of silicon heterojunction (SHJ) solar cells is discussed in this paper in regard to their dependence on the applied amorphous silicon layers, their thicknesses and surface morphology. The emitter system investigated in this work consists of an n-doped, hydrogenized, amorphous silicon carbide a-SiC:H(n) layer with or without a pure, hydrogenized, intrinsic, amorphous silicon a-Si:H(i) intermediate layer. All solar cells were fabricated on p-type FZ-silicon and feature a high-efficiency backside consisting of a SiO 2 passivation layer and a diffused local boron back surface field, allowing us to focus only on the effects of the front side emitter system. The highest solar cell efficiency achieved within this work is 18.5%, which is one of the highest values for SHJ-solar cells using p-type substrates. A dependence of the passivation quality on the surface morphology was only observed for solar cells including an a-Si:H(i) layer. It could be shown that the fill factor suffers from a reduction due to a reduced pseudo fill factor for emitter thicknesses below 11 nm due to a lower passivation quality and/or a higher potential for shunting thorough the a-Si emitter to the crystalline wafer with the conductive indium tin oxide layer. Furthermore, the influence of a variation of the doping gas flow ( PH 3 ) during the plasma enhanced chemical vapor deposition of the doped amorphous silicon carbide a-SiC:H(n) on the solar cell current–voltage characteristic-parameter has been investigated. We could demonstrate that a-SiC:H(n) shows in principle the same dependence on PH 3 -flow as pure a-Si:H(n).

Fiber-optic detection of chlorine in water

Monitoring of the chlorine content represents important issue of the control of water quality. Crucial points of this control are detection of low chlorine concentrations around 1ppm and reversibility of chemical reactions between strong oxidation agent, chlorine and opto-chemical transducers used for the detection. This paper deals with fiber-optic detection of chlorine in water by using a commercially available absorption transducer o-phenylenediamine (o-PDA) electrochemically immobilized onto fiber-optic substrates coated with Indium–Tin-Oxide (ITO).Sensitive layers of the absorption transducer o-PDA were prepared electrochemically by cyclic voltammetry. The layers were applied onto declad segments of polymer-clad silica fibers coated with a thin conductive ITO layer making the electrochemical deposition possible. Prepared detection elements were exposed to aqueous solutions of chlorine of various concentrations and spectral response and time response curves were measured. Oxidized sensitive layers were regenerated chemically by using a solution of sodium thiosulfate. A limit of detection of chlorine in water of about 0.14ppm has been achieved, making the detection of chlorine in water within the hygienic limits feasible.

Optoelectronic devices based on evaporated pentacene films

Aluminium/pentacene Schottky diodes have been fabricated on glass substrates. An ohmic, transparent front contact was prepared by sputtering a highly conductive indium–tin-oxide layer. The pentacene layer was evaporated in high vacuum of a pure (98%) commercially available source. All the samples were grown at room temperature and moderate deposition rates (<10 A/s). Optical measurements evidence absorption peaks at energy positions 1.86, 1.97, 2.13, 2.3 and 2.5 eV, corresponding to singlet states of the lowest unoccupied molecular orbital of pentacene. The current–voltage characteristics show good rectifying behaviours. Finally, a clear antibatic response is observed in the external quantum efficiency of the photodiodes when illuminated through the indium–tin-oxide contact.

ITO films for antireflective and antistatic tube coatings prepared by d.c. magnetron sputtering

A reactive d.c. magnetron sputtering process with relatively high oxygen flow suitable for antireflective and antistatic (ARAS) coatings on display tubes is described. The sputtering conditions and their influence on optical, structural and electrical properties of indium tin oxide (ITO) films are discussed and compared with other ITO sputtering processes from a metallic target. Emphasis is placed on the relation between microstructure, defect structure and conductivity, and on the determination of the optimal process conditions for obtaining fine-grained films for optical applications that can withstand the 460 °C heat treatment during tube assembly. As an example, a simple three-layer broadband ARAS coating is investigated, consisting of a transparent conductive ITO layer, a TiO 2 layer and a SiO 2 layer on top.