Hydrogen‐doped indium oxide (IOH) is a transparent conductive oxide offering great potential to optoelectronic applications because of its high mobility of over 100 cm2 V−1s−1. In films deposited ...statically by RF magnetron sputtering, a small area directly opposing the target center with a higher resistivity and lower crystallinity than the rest of the film has been found via hall‐ and XRD‐measurements, which we attribute to plasma damage. In order to investigate the distribution of particle energies during the sputtering process we have simulated the RF‐sputtering deposition process of IOH by particle‐in‐cell Monte Carlo (PICMC) simulation. At the surface of ceramic sputtering targets, negatively charged oxygen ions are created. These ions are accelerated toward the substrate in the plasma sheath with energies up to 150 eV. They damage the growing film and reduce its crystallinity. The influence of a negatively biased mesh inside the sputtering chamber on particle energies and distributions has been simulated and investigated. We found that the mesh decreased the high‐energetic oxygen ion density at the substrate, thus enabling a more homogeneous IOH film growth. The theoretical results have been verified by XRD X‐ray diffractometry (XRD), 4‐point probe, and hall measurements of statically deposited IOH films on glass.
On a‐Si:H/µc‐Si:H thin film solar cells, the back‐contact and reflector typically consist of a thin ZnO:Al (AZO) buffer layer and a silver layer. The high cost of silver as well as plasmonic ...absorption make it desirable to use a silver‐free backside reflector. We report that a backside contact composed of an AZO transparent conducting oxide (TCO) layer deposited by DC‐magnetron‐sputtering at 180 °C combined with a white paint backside reflector can achieve almost the same solar cell performance as a TCO/silver back contact. The properties of the reflector materials, i.e. silver and commercially available white paint were studied by total and diffuse reflection measurements. The effect of the reflector materials on the performance of the solar cells in mini‐module design were evaluated by current–voltage (I–V) and external quantum efficiency‐measurements. Moreover, the AZO layer used as back contact was optimized to obtain high near‐infrared (NIR)‐transparency while preserving a low resistivity. Altogether, the approach of constructing an a‐Si:H/µc‐Si:H solar cell with a silver‐free backside reflector has been successfully implemented and can still be improved by using a TCO with higher carrier mobility and lower carrier density, thus improving NIR‐light transmission.
The TCO/a-Si:H(p) contact is a critical part of the silicon heterojunction solar cell. At this point, holes from the emitter have to recombine loss free with electrons from the TCO. Since tunneling ...is believed to be the dominant transport mechanism, a high dopant density in both adjacent layers is critical. In contrast to this, it has been reported that high TCO dopant density can reduce field effect passivation induced by the a-Si:H(p) layer. Thus, in this publication, we systematically investigate the influence of a thin (∼10 nm) ITO contact layer with dopant densities ranging from Nd = 1019 - 1021 cm-3 placed between an ITO bulk layer of 70 nm with Nd= 2·1020 cm-3 and the a-Si:H(p) emitter on the J-V characteristics, with the aim to find an optimum Nd. We accompanied our experiments by AFORS-HET simulations, considering trap-assisted tunneling and field dependent mobilities in the a-Si:H(p) layer. As expected, two regimes are visible: For low Nd the devices are limited by inefficient tunneling, resulting in S-shaped J-V characteristics. For high Nd a reduction of the field effect passivation becomes visible in the low injection range. We can qualitatively reproduce these findings using device simulations.
Hydrogen‐doped indium oxide (IOH) is a transparent conductive oxide offering great potential to optoelectronic applications because of its high mobility of over 100 cm
2
V
−1
s
−1
. In films ...deposited statically by RF magnetron sputtering, a small area directly opposing the target center with a higher resistivity and lower crystallinity than the rest of the film has been found via hall‐ and XRD‐measurements, which we attribute to plasma damage. In order to investigate the distribution of particle energies during the sputtering process we have simulated the RF‐sputtering deposition process of IOH by particle‐in‐cell Monte Carlo (PICMC) simulation. At the surface of ceramic sputtering targets, negatively charged oxygen ions are created. These ions are accelerated toward the substrate in the plasma sheath with energies up to 150 eV. They damage the growing film and reduce its crystallinity. The influence of a negatively biased mesh inside the sputtering chamber on particle energies and distributions has been simulated and investigated. We found that the mesh decreased the high‐energetic oxygen ion density at the substrate, thus enabling a more homogeneous IOH film growth. The theoretical results have been verified by XRD X‐ray diffractometry (XRD), 4‐point probe, and hall measurements of statically deposited IOH films on glass.
Hydrogen-doped indium oxide (IOH) is a transparent conductive oxide offering great potential to optoelectronic applications because of its high mobility of over 100cm super(2)V super(-1)s super(-1). ...In films deposited statically by RF magnetron sputtering, a small area directly opposing the target center with a higher resistivity and lower crystallinity than the rest of the film has been found via hall- and XRD-measurements, which we attribute to plasma damage. In order to investigate the distribution of particle energies during the sputtering process we have simulated the RF-sputtering deposition process of IOH by particle-in-cell Monte Carlo (PICMC) simulation. At the surface of ceramic sputtering targets, negatively charged oxygen ions are created. These ions are accelerated toward the substrate in the plasma sheath with energies up to 150eV. They damage the growing film and reduce its crystallinity. The influence of a negatively biased mesh inside the sputtering chamber on particle energies and distributions has been simulated and investigated. We found that the mesh decreased the high-energetic oxygen ion density at the substrate, thus enabling a more homogeneous IOH film growth. The theoretical results have been verified by XRD X-ray diffractometry (XRD), 4-point probe, and hall measurements of statically deposited IOH films on glass.
On a-Si:H/ mu c-Si:H thin film solar cells, the back-contact and reflector typically consist of a thin ZnO:Al (AZO) buffer layer and a silver layer. The high cost of silver as well as plasmonic ...absorption make it desirable to use a silver-free backside reflector. We report that a backside contact composed of an AZO transparent conducting oxide (TCO) layer deposited by DC-magnetron-sputtering at 180 degree C combined with a white paint backside reflector can achieve almost the same solar cell performance as a TCO/silver back contact. The properties of the reflector materials, i.e. silver and commercially available white paint were studied by total and diffuse reflection measurements. The effect of the reflector materials on the performance of the solar cells in mini-module design were evaluated by current-voltage (I-V) and external quantum efficiency-measurements. Moreover, the AZO layer used as back contact was optimized to obtain high near-infrared (NIR)-transparency while preserving a low resistivity. Altogether, the approach of constructing an a-Si:H/ mu c-Si:H solar cell with a silver-free backside reflector has been successfully implemented and can still be improved by using a TCO with higher carrier mobility and lower carrier density, thus improving NIR-light transmission.
We present a vapour phase based approach for the epitaxial growth of Cu sub(2)O with the utilization of elemental copper and oxygen as precursor materials. At present the implementation of MOCVD ...approach is hampered by the absence of the chemical source of Cu with high enough vapour pressure at reasonable temperatures. Moreover, the use of elemental precursors has the advantage of less impurity incorporation during growth opposed to chemical vapour based growth methods. The influence of process parameters on the growth is discussed. High resolution X-ray diffraction measurements reveal the growth of mainly the two (002) and (220) Cu sub(2)O orientations. Precise control of the growth parameters provides the reproducible growth of pure Cu sub(2)O phase without additional CuO formation. Epitaxial growth of Cu sub(2)O is demonstrated on a-plane Al sub(2)O sub(3) in the temperature range of 730 degree C-870 degree C. (copy 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Transparent conductive oxides (TCOs) are employed as contact layers thin film solar cells. They transmit incoming light to the absorber and conduct the generated charge carriers laterally to the ...metal contacts. Thus, the TCO should have a high optical transparency as well as a high electrical conductivity to ensure good solar cell performance. The free charge carriers, which are necessary for the electrical conductivity, also cause free carrier absorption in the near infrared (NIR) spectrum. In order to fulfill the two conflicting requirements mentioned above, it is necessary to reduce the free carrier density and increase the carrier mobility in the TCO at the same time. By accomplishing this, high optical transparency can be achieved while still maintaining a good electrical conductivity. Increasing the transparency of the TCO increases the short-circuit current density (Jsc) in solar cells. 1 On a-Si:H/µc-Si:H thin film solar cells the back-contact and reflector typically consist of a thin ZnO:Al (AZO) buffer layer and a silver layer. The high cost of silver as well as plasmonic absorption make it desirable to use a silver-free backside reflector. We report that a backside contact composed of an AZO transparent conducting oxide (TCO) layer deposited by DC-magnetron-sputtering at 180 °C combined with a white paint backside reflector can achieve almost the same solar cell performance as a TCO/silver back contact. 2 Hydrogen doped indium oxide In2O3:H (IOH) has been widely discussed as a suitable contact layer for thin film solar cells , because of its mobility higher than 100 cm2 / Vs 3. Very low optical absorption can be achieved with this material at resistivities around 350 µΩcm. In this work, a deposition and annealing process for IOH has been developed and optimized. It could be demonstrated that the short circuit current density of a-Si:H/c-Si heterojunction cells as well as CIGS-cells with IOH front contacts could be improved compared to cells with standard ITO- and AZO front contacts. 4 In IOH films deposited statically by rf magnetron sputtering, a small area directly opposing the target center with a higher resistivity and lower crystallinity than the rest of the film has been found via hall- and XRD-measurements, which we attribute to plasma damage. In order to investigate the distribution of particle energies during the sputtering process we have simulated the RF-sputtering deposition process of IOH by Particle-In-Cell Monte-Carlo simulation. At the surface of ceramic sputtering targets, negatively charged oxygen ions are created. These ions are accelerated towards the substrate in the plasma sheath with energies up to 150 eV. Particle energies in this order of magnitude damage the growing film, reduce crystallinity and should be avoided in order to achieve good material properties. The influence of a negatively biased mesh inside the sputtering chamber on particle energies and distributions has been simulated and investigated. We found that the mesh decreased the high energetic oxygen ion density at the substrate, thus enabling a more homogeneous IOH film growth. The theoretical results have been verified by XRD, 4-point-probe and hall measurements of statically deposited IOH films on glass. 5 1 H. Scherg-Kurmes, S. Seeger, S. Körner, R. Schlatmann, B. Rech, und B. Szyszka, „Optimization of the post-deposition annealing process of high mobility In2O3:H for photovoltaic applications“, Thin Solid Films, Bd. 599, S. 78–83, 2016. 2 H. Scherg-Kurmes u. a., „Comparative study of backside reflectors on a-Si:H/µc-Si:H thin film solar cells“, Phys. Status Solidi A, Bd. 211, S. 2078–81, 2014. 3 T. Koida, H. Fujiwara, und M. Kondo, „Hydrogen-doped In2O3 as High-mobility Transparent Conductive Oxide“, Jpn. J. Appl. Phys., Bd. 46, Nr. 28, S. L685–L687, 2007. 4 H. Scherg-Kurmes u. a., „High mobility In2O3:H as contact layer for a-Si:H/c-Si heterojunction and mc-Si:H thin film solar cells“, Thin Solid Films, Nr. 0, S. , 2015. 5 H. Scherg-Kurmes u. a., „Improvement of the homogeneity of high mobility In2O3:H films by sputtering through a mesh electrode studied by Monte Carlo simulation and thin film analysis“, Phys. Status Solidi A, Bd. 213, Nr. 9, S. 2310–2316, 2016.
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