%0 Journal Article %J Solar Energy Materials and Solar Cells %D 2013 %T Modeling of optical and energy performance of tungsten-oxide-based electrochromic windows including their intermediate states %A Sunnie H.N. Lim %A Jan Isidorsson %A Lizhong Sun %A B. Leo Kwak %A André Anders %K Electrochromic windows %K Energy efficient window modeling %K Energy simulation %K Smart windows %X
Tungsten-oxide-based electrochromic (EC) windows are currently the most robust and matured dynamic windows where the transmittance of visual light and near-infrared radiation can be controlled by a small applied voltage. In its standard application, the window is commonly either in its clear or colored state. In this contribution, we study the optical and energy performance of such window in the fully bleached and fully colored state as well as when it is kept in intermediate states. Different configurations in terms of placement of the EC layer stack and possible additional low-emissivity (low-E) coating within the insulated glass unit are considered. Using optical data and software tools we find that even a small coloration has a significant effect on the energy performance because the solar heat gain coefficient is readily reduced by the absorption of the EC layer stack. We compare the performance of the EC windows to commercially available solar-control (spectrally selective) low-E windows.
%B Solar Energy Materials and Solar Cells %V 108 %P 129 - 135 %8 1/2013 %! Solar Energy Materials and Solar Cells %R 10.1016/j.solmat.2012.09.010 %0 Journal Article %J Journal of Materials Research %D 2012 %T Improved structural and electrical properties of thin ZnO:Al films by dc filtered cathodic arc deposition %A Yuankun Zhu %A Rueben J. Mendelsberg %A Sunnie H.N. Lim %A Jiaqi Zhu %A Jiecai Han %A André Anders %K physical vapor deposition %K Plasma deposition %K Transparent conductor %XTransparent conducting oxide films are usually several 100-nm thick to achieve the required low sheet resistance. In this study, we show that the filtered cathodic arc technique produces high-quality low-cost ZnO:Al material for comparably smaller thicknesses than achieved by magnetron sputtering, making arc deposition a promising choice for applications requiring films less than 100-nm thick. A mean surface roughness less than 1 nm is observed for ZnO:Al films less than 100-nm thick, and 35-nm-thick ZnO:Al films exhibit Hall mobility of 28 cm2/Vs and a low resistivity of 6.5 × 10−4 Ωcm. Resistivity as low as 5.2 × 10−4 Ωcm and mobility as high as 43.5 cm2/Vs are obtained for 135-nm films.
%B Journal of Materials Research %V 27 %P 857 - 862 %8 3/2012 %N 05 %! J. Mater. Res. %R 10.1557/jmr.2011.342 %0 Journal Article %J Journal of Physics D: Applied Physics %D 2011 %T Achieving high mobility ZnO:Al at very high growth rates by dc filtered cathodic arc deposition %A Rueben J. Mendelsberg %A Sunnie H.N. Lim %A Yuankun Zhu %A Joe Wallig %A Delia J. Milliron %A André Anders %XAchieving a high growth rate is paramount for making large-area transparent conducting oxide coatings at a low cost. Unfortunately, the quality of thin films grown by most techniques degrades as the growth rate increases. Filtered dc cathodic arc is a lesser known technique which produces a stream of highly ionized plasma, in stark contrast to the neutral atoms produced by standard sputter sources. Ions bring a large amount of potential energy to the growing surface which is in the form of heat, not momentum. By minimizing the distance from cathode to substrate, the high ion flux gives a very high effective growth temperature near the film surface without causing damage from bombardment. The high surface temperature is a direct consequence of the high growth rate and allows for high-quality crystal growth. Using this technique, 500–1300 nm thick and highly transparent ZnO : Al films were grown on glass at rates exceeding 250 nm min−1 while maintaining resistivity below 5 × 10−4 Ω cm with electron mobility as high as 60 cm2 V−1 s−1.
%B Journal of Physics D: Applied Physics %V 44 %P 232003-232007 %N 23 %2 LBNL-5585E %! J. Phys. D: Appl. Phys. %& 232003 %R 10.1088/0022-3727/44/23/232003 %0 Journal Article %J Thin Solid Films %D 2009 %T High quality ZnO:Al transparent conducting oxide films synthesized by pulsed filtered cathodic arc deposition %A André Anders %A Sunnie H.N. Lim %A Kin Man Yu %A Joakim Andersson %A Johanna Rosén %A Mike McFarland %A Jeff Brown %XAluminum-doped zinc oxide, ZnO:Al or AZO, is a well-known n-type transparent conducting oxide with great potential in a number of applications currently dominated by indium tin oxide (ITO). In this study, the optical and electrical properties of AZO thin films deposited on glass and silicon by pulsed filtered cathodic arc deposition are systematically studied. In contrast to magnetron sputtering, this technique does not produce energetic negative ions, and therefore ion damage can be minimized. The quality of the AZO films strongly depends on the growth temperature while only marginal improvements are obtained with post-deposition annealing. The best films, grown at a temperature of about 200°C, have resistivities in the low to mid 10-4Ω cm range with a transmittance better than 85% in the visible part of the spectrum. It is remarkable that relatively good films of small thickness (60 nm) can be fabricated using this method.
%B Thin Solid Films %G eng %L LBNL-1881E %1Windows and Daylighting Group
%2 LBNL-1881E %0 Journal Article %J Journal of Physics: Condensed Matter %D 2008 %T The structure and electron energy loss near edge structure of tungsten oxide thin films prepared by pulsed cathodic arc deposition and plasma-assisted pulsed magnetron sputtering %A Matthew R. Field %A Dougal G. McCulloch %A Sunnie H.N. Lim %A André Anders %A Vicki J. Keast %A R.W. Burgess %XThe microstructure and energy-loss near-edge structure (ELNES) of pulsed cathodic arc and pulsed magnetron sputtered WO3 thin films were investigated. It was found that the cathodic arc deposited material consisted of the α-WO3 phase with a high degree of crystallinity. In contrast, the magnetron sputtered material was highly disordered making it difficult to determine its phase. A self-consistent real space multiple scattering approach was used to calculate the NES of the various phases of WO3. Each phase was found to exhibit a unique NES allowing different phases of WO3 to be identified. The real space approach also allowed the origin of the main features in the NES to be investigated as the cluster size increased. The calculated NES for the room temperature γ-WO3 was found to compare well to previous X-ray absorption spectra and to NES obtained by full-potential band structure calculation.
%B Journal of Physics: Condensed Matter %V 20 %P 175216 %8 04/2008 %G eng %1Windows and Daylighting Group
%2 LBNL-580E %R 10.1088/0953-8984/20/17/175216 %0 Journal Article %J Review of Scientific Instruments %D 2006 %T Filtered cathodic arc deposition with ion-species-selective bias %A André Anders %A Nitisak Pasaja %A Sakon Sansongsiri %A Sunnie H.N. Lim %XA dual-cathode arc plasma source was combined with a computer-controlled bias amplifier such as to synchronize substrate bias with the pulsed production of plasma. In this way, bias can be applied in a material-selective way. The principle has been applied to the synthesis metal-doped diamond-like carbon films, where the bias was applied and adjusted when the carbon plasma was condensing, and the substrate was at ground when the metal was incorporated. In doing so, excessive sputtering by too-energetic metal ions can be avoided while the sp3/sp2 ratio can be adjusted. It is shown that the resistivity of the film can be tuned by this species-selective bias. The principle can be extended to multiple-material plasma sources and complex materials.
%B Review of Scientific Instruments %G eng %L LBNL-61733 %1Windows and Daylighting Group
%2 LBNL-61733 %0 Journal Article %J Surface and Coatings Technology %D 2006 %T Plasma biasing to control the growth conditions of diamond-like carbon %A André Anders %A Nitisak Pasaja %A Sunnie H.N. Lim %A Tim C. Petersen %A Vicki J. Keast %K Diamond-like carbon films %K Electron energy loss spectroscopy %K Plasma bias %K Substrate bias %K transmission electron microscopy %XIt is well known that the structure and properties of diamond-like carbon, and in particular the sp3/sp2 ratio, can be controlled by the energy of the condensing carbon ions or atoms. In many practical cases, the energy of ions arriving at the surface of the growing film is determined by the bias applied to the substrate. The bias causes a sheath to form between substrate and plasma in which the potential difference between plasma potential and surface potential drops. In this contribution, we demonstrate that the same results can be obtained with grounded substrates by shifting the plasma potential. This plasma biasing (as opposed to substrate biasing) is shown to work well with pulsed cathodic carbon arcs, resulting in tetrahedral amorphous carbon (ta-C) films that are comparable to the films obtained with the conventional substrate bias. To verify the plasma bias approach, ta-C films were deposited by both conventional and plasma bias and characterized by transmission electron microscopy (TEM) and electron energy loss spectrometry (EELS). Detailed data for comparison of these films are provided.
%B Surface and Coatings Technology %V 201 %P 4628-4632 %8 01/2007 %G eng %N 8 %1Windows and Daylighting Group
%2 LBNL-59023 %& 4628 %R 10.1016/j.surfcoat.2006.09.313 %0 Journal Article %J Applied Physics Letters %D 2006 %T Smoothing of ultrathin silver films by transition metal seeding %A André Anders %A Eungsun Byon %A Dong-Ho Kim %A Kentaro Fukuda %A Sunnie H.N. Lim %XThe nucleation and coalescence of silver islands on coated glass was investigated by in-situ measurements of the sheet resistance. Sub-monolayer amounts of transition metals (Nb, Ti, Ni, Cr, Zr, Ta, and Mo) were deposited prior to the deposition of silver. It was found that some, but not all, of the transition metals lead to coalescence of silver at nominally thinner films with smoother topology. The smoothing effect of the transition metal at sub-monolayer thickness can be explained by a thermodynamic model of surface energies.
%B Applied Physics Letters %G eng %L LBNL-59621 %1Windows and Daylighting Group
%2 LBNL-59621