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Natively textured ZnO layers deposited by the expanding thermal plasma CVD technique between 150 and 350°C at a deposition rate between 0.65 and 0.75 nm/s have been investigated with respect to their suitability as front electrode material for amorphous silicon pin solar cells in comparison to reference SnO2:F (Asahi U-type). At higher substrate temperature and with growing thickness, the surface roughness of the ZnO films increases. Layers with electrical (sheet resistance <10 Ω/□), optical (transmittance > 80%) and morphological (surface texture) properties comparable to Asahi U-type SnO2:F have been obtained. Preliminary solar cells deposited on ZnO show an efficiency approaching 10%. cop. 2001 Elsevier Science B.V.

A new method for low temperature deposition of surface textured ZnO is presented utilizing an expanding thermal plasma created by a cascaded arc. Films have been deposited at 150-350°C at a rate of typically 0.65-0.75 nm/s, exhibiting low sheet resistance (> 10 Ω/□), high transmittance (>80%) and a rough surface texture. Surface roughness increases with increasing deposition temperature and film thickness. First pin a-Si:H solar cells deposited on this ZnO show initial efficiencies approaching 10%. cop. 2000 IEEE.

The corrosion behavior of Cr(VI) and Cr(III) treated zinc has been studied using scanning Kelvin probe (SKP), potentiodynamic polarization and elctrochemical impedance spectroscopy (EIS). The Volta potentials measured on the Cr(VI) or the CR(III)-A treated zinc area by SKP in a humid chamber are more negative than on the untreated zinc area, which is in agreement with their corrosion potential measured in 0.01 M NaCl solution. The polarization resistance measurements show that both the Cr(VI) and the Cr(III) coatings can decrease the corrosion rate of zinc. The Cr(III)-B coating is thicker than the Cr(III)-A coating, and its corrosion resistance is greater than that of the Cr(III)-A coating. However, the inhibition of the corrosion of zinc by Cr(IV) coating is more effective than by the Cr(III) coatings. Pt and Zn electrodes in NaCl solution with and without dichromate were also investigated. The results show that the Cr(VI) coatings can protect zinc in two ways: as a barrier layer and as a passivating inhibitor ("self-healing" effect).

Inverted polymer:fullerene solar cells with ZnO and MoO3 transport layers are demonstrated. ZnO films are prepared through spin casting of a zinc acetylacetonate hydrate solution, followed by low temperature annealing under ambient conditions. The performance of solar cells with an inverted structure is shown to be equivalent to that of conventional cells with a bottom-anode-top-cathode configuration for three efficient polymer:fullerene systems. © 2010 Elsevier B.V. All rights reserved.

Natively textured ZnO layers for the application as front electrode material in amorphous silicon pin solar cells have been deposited by Expanding Thermal Plasma Chemical Vapor Deposition. Films deposited in the temperature regime from 150 to 350°C at a rate between 0.65 and 0.75 nm/s have been characterteed with respect to their optical, electrical and structural properties. Results comparable to Asahi U-type SnO2:F have been obtained for these layers. First solar cells on ZnO, which was deposited at 250°C and 350°C, show an efficiency approaching 10%, only slightly lower than on Asahi U-type SnO2:F. cop. 2000 IEEE.

The throwing power of the Zinc-Hydrogel Anode for sacrificial protection of steel in concrete was studied in the laboratory under controlled environments. The anode to steel ratio in the specimens was 1. The corrosion state of the rebar is moderate. The results indicate that for a concrete resistivity of 600 Qm and higher the ohmic drop in the concrete is an important factor in the lateral protection of steel with diameter of 8 mm and a cover of 15 mm. For 600 Qm a lateral throwing power of 220 mm or more was obtained, while for 1900 SZm this decreases to less than 120 mm. Our results on the throwing power in the depth direction indicate that for a concrete resistivity between 600 and 1000 Qm protection of two corroding rebar layers of 8 mm diameter at two different depths between 0 and 150 mm can be obtained. The measurements show that for a higher concrete resistivity proper protection is questionable

Area-selective atomic layer deposition (ALD) of ZnO was achieved on SiO2 seed layer patterns on Hterminated silicon substrates, using diethylzinc (DEZ) as the zinc precursor and H2O as the coreactant. The selectivity of the ALD process was studied using in situ spectroscopic ellipsometry and scanning electron microscopy, revealing improved selectivity for increasing deposition temperatures from 100 to 300 °C. The selectivity was also investigated using transmission electron microscopy and energy-dispersive X-ray spectroscopy. Density functional theory (DFT) calculations were performed to corroborate the experimental results obtained and to provide an atomic-level understanding of the underlying surface chemistry. A kinetically hindered proton transfer reaction from the H-terminated Si was conceived to underpin the selectivity exhibited by the ALD process. By combining the experimental and DFT results, we suggest that the trend in selectivity with temperature may be due to a strong DEZ or H2O physisorption on the H-terminated Si that hampers high selectivity at low deposition temperature. This work highlights the deposition temperature as an extra process parameter to improve the selectivity.

The deposition of zinc oxide has been performed by atmospheric pressure chemical vapor deposition and trends in growth rates are compared with the literature. Diethylzinc and tertiary butanol were used as the primary reactants and deposition rates above 800 nm/minwere obtained. The reaction kineticswere studied and detailed process modeling based on a reaction mechanism that includes the formation of an alkylzinc alkoxide intermediate product is discussed. Thismechanism can explain the temperature dependent variety in deposition profiles observed in the static deposition experiments. The capability of modeling to gain insight in the local process conditions inside a reactor is demonstrated. © 2013 Elsevier B.V. All rights reserved.

Sputtered aluminum doped zinc oxide (ZnO:Al) layers on borosilicate glass were exposed to damp heat (85 C/85% relative humidity) for 2876 h to accelerate the physical and chemical degradation behavior. The ZnO:Al samples were characterized by electrical, compositional and optical measurements before and after degradation. Hall measurements show that the carrier concentration stayed constant, while the Hall mobility decreased and the overall resistivity thus increased. This can be explained by the increase of potential barriers at the grain boundaries due to the occurrence of space charge regions caused by additional electron trapping sites. X-Ray Diffraction and optical measurements show that the crystal structure and transmission in the range 300-1100 nm do no change, hereby confirming that the bulk structure stays constant. Furthermore, on the surface, white spots appeared, containing elements that migrated from the glass, like silicon and calcium, which reacted with elements from the environment, including oxygen, carbon and chlorine. Depth profiling showed that the increase of the potential barrier is caused by the diffusion of H 2O/OH- through the grain boundaries leading to the formation of Zn(OH)2 or similar species or adsorption of species. They also indicate the presence of chloride and sulfide in the top layer and the possible presence of Zn5(OH)8Cl2·H 2O and Zn4SO4(OH)6·nH 2O © 2013 Elsevier B.V.

The deposition of zinc oxide has been performed by atmospheric pressure chemical vapor deposition and trends in growth rates are compared with the literature. Diethylzinc and tertiary butanol were used as the primary reactants and deposition rates above 800 nm/min were obtained. The reaction kinetics were studied and detailed process modeling based on a reaction mechanism that includes the formation of an alkylzinc alkoxide intermediate product is discussed. This mechanism can explain the temperature dependent variety in deposition profiles observed in the static deposition experiments. The capability of modeling to gain insight in the local process conditions inside a reactor is demonstrated. © 2013 Elsevier B.V.

In this work a technology to fabricate low-voltage amorphous gallium-indium-zinc oxide thin film transistors (TFTs) based integrated circuits on 25 µm foils is presented. High performance TFTs were fabricated at low processing temperatures (<150 °C) with field effect mobility around 17 cm2 /V s. The technology is demonstrated with circuit building blocks relevant for radio frequency identification applications such as high-frequency functional code generators and efficient rectifiers. The integration level is about 300 transistors. © 2011 American Institute of Physics.

The corrosion properties of electrodeposited zinc-cobalt-iron (Zn-Co-Fe) alloys (up to 40 wt.% Co and 1 wt.% Fe) on steel were studied by using various electrochemical techniques and compared with zinc (Zn) and cadmium (Cd) coatings in 3.5% NaCl solution. It was found that with an increase in Co content in the coating the open circuit potential (OCP) became more positive than that of the zinc coating. For Co contents higher than 30 wt.% the OCP shifted close to that of Cd, but still remained electronegative to the steel substrate. Zn-Co-Fe coatings with ≥ 30 wt.% Co + 1 wt.% Fe are nano-crystalline in nature and show superior corrosion resistance as compared to the Zn, low Co content Zn-Co-Fe and Cd coatings. During longer immersion, Zn-Co-Fe alloys with 34-40 wt.% Co became more noble to steel due to dezincification of the surface but the corresponding corrosion current density decreased. The corrosion resistance determined by the electrochemical techniques are confirmed by salt spray testing showing the superior corrosion resistance for Cd and high Co content Zn-Co-Fe alloys and poor performance of alloys with lower Co contents and pure Zn. © 2008 Elsevier B.V. All rights reserved.

Thin-film transistors (TFTs) are the fundamental building blocks of today's display industry. To achieve higher drive currents and device density, it is essential to scale down the channel lengths of TFTs. To be able to fabricate short-channel TFTs in large volumes is also equally important in order to realize lower fabrication costs and higher throughput. In this paper, we demonstrate the application of substrate conformal imprint lithography (SCIL) to pattern top-gate (TG) self-aligned (SA) amorphous indium gallium zinc oxide TFTs down to channel length L G = 450 nm with good device scaling properties resulting in average field-effect mobility (? FE ) = ? 10 cm 2 ·V -1 ·s -1 , V ON = ? 0.5 V, and subthreshold swing (SS) = ? 0.3 V/decade. The device performance as a function of channel length outlines the importance of dopant diffusion control for realizing submicrometer SA TFTs. The results demonstrate the compatibility of SCIL-based large-area patterning for the realization of submicrometer TG SA TFTs with a potential for high throughput. © 2019 IEEE.

Ultralow-power gas sensing devices need to operate without an energy consuming heater element. This requires the design of sensing devices that are so efficient that they can operate at room temperature (RT). Here, we report on the RT sensing performance of atomic layer deposition (ALD) prepared i-ZnO and Al-doped ZnO sensing devices. The sensitivity of these devices has been catalytically enhanced with ALD Pt nanoparticles (NPs). It was shown that the size distribution of the Pt NPs can be controlled by the number of Pt-ALD cycles. The Pt-enhanced sensing devices showed a reversible, proportional change in current response at RT upon exposure to O2 and CO. O2 could be detected, diluted in N2, down to 0.5%. CO could be detected, diluted in N2 in the presence of O2 and H2O, down to 20 ppm. Reference devices without Pt NPs showed no response, indicating the importance of the Pt NPs for the sensing mechanism. cop. The Electrochemical Society.

Flexible large-area organic light-emitting diodes (OLEDs) require highly conductive and transparent anodes for efficient and uniform light emission. Tin-doped indium oxide (ITO) is the standard anode in industry. However, due to the scarcity of indium, alternative anodes that eliminate its use are highly desired. Here an indium-free anode is developed by a combinatorial study of zinc oxide (ZnO) and tin oxide (SnO2), both composed of earth-abundant elements. The optimized Zn-Sn-O (ZTO) films have electron mobilities of up to 21 cm2 V-1 s-1, a conductivity of 245 S cm-1, and <5% absorptance in the visible range of the spectrum. The high electron mobilities and low surface roughness (<0.2 nm) are achieved by producing dense and void-free amorphous layers as confirmed by transmission electron microscopy. These ZTO layers are evaluated for OLEDs in two anode configurations: i) 10 cm2 devices with ZTO/Ag/ZTO and ii) 41 cm2 devices with ZTO plus a metal grid. The ZTO layers are compatible with OLED processing steps and large-area white OLEDs fabricated with the ZTO/grid anode show better performance than those with ITO/grid anodes. These results confirm that ZTO has the potential as an In-free and Earth-abundant alternative to ITO for large-area flexible OLEDs. cop. 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

In this paper, we present the fabrication and characterization of highly flexible indium-gallium-zinc-oxide (IGZO)-based thin-film transistors (TFTs) and integrated circuits on a transparent and thin polymer substrate. Mechanical reliability tests are performed under bending conditions down to a bending radius of 2 mm. All the TFT parameters show only a weak dependence on mechanical strain. TFTs can withstand bending strain up to 0.75% without any significant change in the device operation. Mechanical reliability is further demonstrated to a higher TFT integration level by ring oscillators and 8-b transponder chips operating at a bending radius of 2 mm. cop. 1963-2012 IEEE.

Textured transparent conductors are widely used in thin-film silicon solar cells. They lower the reflectivity at interfaces between different layers in the cell and/or cause an increase in the path length of photons in the Si absorber layer, which both result in an increase in the number of absorbed photons and, consequently, an increase in short-circuit current density (Jsc) and cell efficiency. Through optical simulations, we recently obtained strong indications that texturing of the transparent conductor in copper indium gallium (di-)selenide (CIGS) solar cells is also optically advantageous. Here, we experimentally demonstrate that the Jsc and efficiency of CIGS solar cells with an absorber layer thickness (dCIGS) of 0.85 μm, 1.00 μm and 2.00 μm increase through application of a moth-eye textured resist with a refractive index that is sufficiently similar to AZO (nresist = 1.792 v s. nAZO = 1.913 at 633 nm) to avoid large optical losses at the resist-AZO interface. On average, Jsc increases by 7.2%, which matches the average reduction in reflection of 7.0%. The average relative increase in efficiency is slightly lower (6.0%). No trend towards a larger relative increase in Jsc with decreasing dCIGS was observed. Ergo, the increase in Jsc can be fully explained by the reduction in reflection, and we did not observe any increase in Jsc based on an increased photon path length.