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1. The Nuclear Structure of ⁷⁴ Ge from Inelastic Neutron Scattering

   https://doi.org/10.1051/epjconf/202532901005  

   Peters, E E; Yates, S W; Brown, B A; Ramirez, A_P D; Mukhopadhyay, S (January 2025, EPJ Web of Conferences)

   Jentschel, M (Ed.)

   The low-lying structure of⁷⁴Ge has been studied with γ-ray detection following inelastic neutron scattering. From excitation function and angular distribution data, the levels and transitions have been characterized including level spins and lifetimes, branching ratios, and multipole mixing ratios. In addition, a number of levels found in the literature for⁷⁴Ge appear to be erroneously placed. Upon removal of these states from the level scheme, excellent agreement with large-scale shell-model calculations was obtained. 

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2. Measurement of Volume Changes and Associated Stresses in Ge Electrodes Due to Na/Na ⁺ Redox Reactions

   https://doi.org/10.1149/1945-7111/abd5fc  

   Rakshit, Subhajit; Pakhare, Akshay S.; Ruiz, Olivia; Khoshi, M. Reza; Detsi, Eric; He, Huixin; Sethuraman, Vijay A.; Nadimpalli, Siva P. V. (January 2021, Journal of The Electrochemical Society)

   In situ electrochemical cells were assembled with an amorphous germanium (a-Ge) film as working electrode and sodium foil as reference and counter electrode. The stresses generated in a-Ge electrodes due to electrochemical reaction with sodium were measured in real-time during the galvanostatic cycling. A specially designed patterned a-Ge electrode was cycled against sodium and the corresponding volume changes were measured using an AFM; it was observed that sodiation/desodiation of a-Ge results in more than 300% volume change, consistent with literature. The potential and stress response showed that the a-Ge film undergoes irreversible changes during the first sodiation process, but the subsequent desodiation/sodiation cycles are reversible. The stress response of the film reached steady-state after the initial sodiation and is qualitatively similar to the response of Ge during lithiation, i.e., initial linear elastic response followed by extensive plastic deformation of the film to accommodate large volume changes. However, despite being bigger ion, sodiation of Ge generated lower stress levels compared to lithiation. Consequently, the mechanical dissipation losses associated with plastic deformation are lower during sodiation process than it is for lithiation. 

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3. Local ordering in Ge/Ge–Sn semiconductor alloy core/shell nanowires revealed by extended x-ray absorption fine structure (EXAFS)

   https://doi.org/10.1063/5.0136746  

   Lentz, J. Zach; Woicik, J. C.; Bergschneider, Matthew; Davis, Ryan; Mehta, Apurva; Cho, Kyeongjae; McIntyre, Paul C. (February 2023, Applied Physics Letters)

   Short-range atomic order in semiconductor alloys is a relatively unexplored topic that may promote design of new materials with unexpected properties. Here, local atomic ordering is investigated in Ge–Sn alloys, a group-IV system that is attractive for its enhanced optoelectronic properties achievable via a direct gap for Sn concentrations exceeding ≈10 at. %. The substantial misfit strain imposed on Ge–Sn thin films during growth on bulk Si or Ge substrates can induce defect formation; however, misfit strain can be accommodated by growing Ge–Sn alloy films on Ge nanowires, which effectively act as elastically compliant substrates. In this work, Ge core/Ge 1−x Sn x ( x ≈  0.1) shell nanowires were characterized with extended x-ray absorption fine structure (EXAFS) to elucidate their local atomic environment. Simultaneous fitting of high-quality EXAFS data collected at both the Ge K-edge and the Sn K-edge reveals a large (≈ 40%) deficiency of Sn in the first coordination shell around a Sn atom relative to a random alloy, thereby providing the first direct experimental evidence of significant short-range order in this semiconductor alloy system. Comparison of path length data from the EXAFS measurements with density functional theory simulations provides alloy atomic structures consistent with this conclusion. 

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4. Photodriven Elimination of Chlorine From Germanium and Platinum in a Dinuclear Pt ^II →Ge ^IV Complex

   https://doi.org/10.1002/anie.202107485  

   Karimi, Mohammadjavad; Tabei, Elham S.; Fayad, Remi; Saber, Mohamed R.; Danilov, Evgeny O.; Jones, Cameron; Castellano, Felix N.; Gabbaï, François P. (September 2021, Angewandte Chemie International Edition)

   Abstract Searching for a connection between the two‐electron redox behavior of Group‐14 elements and their possible use as platforms for the photoreductive elimination of chlorine, we have studied the photochemistry of [(o‐(Ph₂P)C₆H₄)₂Ge^IVCl₂]Pt^IICl₂and [(o‐(Ph₂P)C₆H₄)₂ClGe^III]Pt^IIICl₃, two newly isolated isomeric complexes. These studies show that, in the presence of a chlorine trap, both isomers convert cleanly into the platinum germyl complex [(o‐(Ph₂P)C₆H₄)₂ClGe^III]Pt^ICl with quantum yields of 1.7 % and 3.2 % for the Ge^IV–Pt^IIand Ge^III–Pt^IIIisomers, respectively. Conversion of the Ge^IV–Pt^IIisomer into the platinum germyl complex is a rare example of a light‐induced transition‐metal/main‐group‐element bond‐forming process. Finally, transient‐absorption‐spectroscopy studies carried out on the Ge^III–Pt^IIIisomer point to a ligand arene–Cl^.charge‐transfer complex as an intermediate. 

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5. Ultra-low temperature synthesis of Ge-based optical materials and devices on Si using GeH ₃ Cl

   https://doi.org/10.1039/d2tc02862j  

   Zhang, Aixin; Mircovich, Matthew A.; Ringwala, Dhruve A.; Poweleit, Christian D.; Roldan, Manuel A.; Menéndez, José; Kouvetakis, John (September 2022, Journal of Materials Chemistry C)

   We describe an alternative strategy to the fabrication of Ge–Sn based materials on Si by using chlorogermane (GeH 3 Cl) instead of the specialty Ge hydrides (Ge 2 H 6 , Ge 3 H 8 , Ge 4 H 10 ) currently employed as ultra-low temperature sources of Ge. This simpler and potentially more practical chlorinated derivative is obtained in high yields and in research-grade purity by direct reactions of commercial GeH 4 and SnCl 4 and exhibits favorable physical and chemical properties that make it an effective source of Ge for a wide range of chemical vapor deposition (CVD) processing conditions. As a proof-of concept, we have employed GeH 3 Cl to demonstrate deposition of pure Ge and GeSn hetero-structures on large-area Si wafers, at conditions compatible with current specialty methods for next generation technologies but with higher deposition efficiency, ensuring an optimal use of the Ge feedstock. In the case of pure Ge, GeH 3 Cl has enabled growth of thick and uniform Ge layers with flat surfaces and relaxed microstructures at 330–360 °C, exhibiting lower residual doping than obtained by alternate Ge hydride methods. GeH 3 Cl allows for in situ doping with the same facility as the Ge hydrides, and this has enabled the design and fabrication of homo-structure pin photodetectors exhibiting low dark current densities and closer to ideal optical collection efficiencies when compared to devices produced by other Ge-on-Si approaches. In the case of GeSn, the high reactivity of GeH 3 Cl toward Sn hydrides has enabled the formation of mono-crystalline alloy layers at ultra-low temperatures between 200–300 °C and conditions akin to molecular beam epitaxy (MBE). Combined, these results suggest an intriguing potential for this new CVD process in the device-application space. The deployment of GeH 3 Cl as a highly reactive low-temperature Ge-source could not only improve on the current wasteful methods that use GeH 4 , but also eliminate the need for the higher-cost polygermanes. 

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