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1. Alloy Loss Mitigation Through Use of Barrier Layers During CdCl2 Processing of Cd0.60Zn0.4Te and Cd0.87Mg0.13Te

   https://doi.org/10.1109/PVSC.2018.8548155  

   Reich, Carey L.; Swanson, Drew E.; Onno, Arthur; Shimpi, Tushar; Metzger, Wyatt K.; Sampath, Walajabad S.; Holman, Zachary C. (June 2018, 2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC))
2. A new semiconductor: Ti0.5Mg0.5N(001)

   https://doi.org/10.1109/NANOTECH.2018.8653564  

   Wang, Baiwei; Gall, Daniel (November 2018, 2018 IEEE Nanotechnology Symposium (ANTS), Albany, NY, 2018)

   Ti0.5Mg0.5N has recently been predicted to be a semiconductor with a 1.3 eV band gap and promising properties for thermoelectric and plasmonic devices. As a first step towards experimental validation, epitaxial Ti0.5Mg0.5N(001) layers are deposited on MgO(001) by reactive magnetron co-sputtering from titanium and magnesium targets at 600 °C in pure N2 atmospheres. X-ray diffraction ω-2θ scans, ω-rocking curves, φ-scans, and high resolution reciprocal space maps show that Ti0.5Mg0.5N alloys form a pseudobinary rocksalt structure and are single crystals with a cube-on-cube epitaxial relationship with the substrate: (001)TiMgN║(001)MgO and [100]TiMgN║[100]MgO. A 275-nm-thick Ti0.5Mg0.5N layer is fully relaxed and exhibits a 002 ω-rocking curve width ω = 0.73°, while a 36-nm-thick layer is fully strained and has a ω = 0.49°. These results indicate a thickness-dependent strain state which suggests a critical thickness for misfit dislocation nucleation and glide which is between 36 and 275 nm. A measured negative temperature coefficient of resistivity in combination with a low optical absorption coefficient of 0.25 × 105 cm 1 for λ = 740 nm, and a vanishing density of states at the Fermi level measured by x-ray photoelectron spectroscopy support the prediction that Ti0.5Mg0.5N is a semiconductor. 

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3. Thermally Tunable Far-Infrared Metasurfaces Enabled by Ge2Sb2Te5 Phase-Change Material

   https://doi.org/10.1109/RAPID.2018.8508956  

   Yahiaoui, Riad; Mathews, Jay; Burrow, Joshua A.; Agha, Imad; Sevison, Gary; Urbas, Augustine M.; Sarangan, Andrew; Searles, Thomas A. (August 2018, IEEE Rapid)

   The development of active metadevices continues to present keystone challenges in fields of plasmonics and photonics. Here, we demonstrate an analogue of electromagnetically induced transparency (EIT) effect in a far-infrared metasurface device via near-field coupling of bright and quasi-dark resonances resonating at nearly the same frequency with contrasting line widths. The proposed metasurface was further optimized numerically in order to demonstrate a reconfiguration effect (frequency-shift of the spectral response). The tunability property of the device is achieved by incorporating a thin layer of Ge 2 Sb 2 Te 5 (GST), a temperature-driven phase change material (PCM). Theoretical analysis based on a coupled Lorentz oscillator model explains the physical mechanism in the proposed design and shows a good agreement with the observed results. Such active hybrid EIT metadevices could have applications in tunable slow-light effects, delay bandwidth management and ultrafast laser induced switching. 

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4. Co-Sublimated Polycrystalline Cd1-xZnx Te Films for Multi-junction Solar Cells

   https://doi.org/10.1109/PVSC.2018.8547657  

   Shimpi, Tushar; Swanson, Drew; Reich, Carey; Kephart, Jason; Kindvall, Anna; Pandey, Ramesh; Holman, Zachary; Barth, Kurt; Sampath, Walajabad (June 2018, 2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC))
5. Dramatic Recrystallization During CdCl2 Treatment of Evaporated CdTe Thin Filmsa

   https://doi.org/10.1109/PVSC.2018.8547287  

   Falbaum, Barrett S.; Winger, Joshua R.; Scarpulla, Michael A. (June 2018, 2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC))

   In this work, we report the different effects of CdCl 2 treatment on CdTe films deposited by thermal evaporation onto CdS and MgZnO (MZO) buffer layers. The main finding, which is relevant for understanding recent advances in CdTe device efficiency, is that few-μm thick CdTe films deposited on MZO can be induced to completely recrystallize forming a film consisting of grains that span the film thickness and are up to 30 μm laterally. On CdS buffer layers, the changes in microstructure with Cl treatment are much less pronounced and the final microstructure is less ideal for thin film photovoltaics. We propose a thermodynamic framework for understanding the microstructural changes during CdCl 2 treatment which can assist in understanding the wide range of behaviors observed across the many CdTe thin film solar cell fabrication procedures. 

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