More Like this

1. Tantalum

   Zi-Ling Xue Tabitha M. Cook ( January 2021 , Comprehensive Coordination Chemistry III)

   Edwin C. Constable Gerard Parkin Lawrence Que Jr (Ed.)

   This review on coordination chemistry of tantalum covers the literature between 2003 and 2018. Tantalum complexes with ligands based on groups 15 (nitrogen, phosphorus, arsenic), 16 (oxygen, sulfur, selenium, tellurium), and 17 (fluorine, chlorine, bromine) as well as with mixed-donor ligands are the focus. Coverage of organometallic complexes is selective to give readers a more comprehensive understanding of the coordination chemistry of tantalum. Complexes with hydride and boron- and carbon-based ligands, including alkylidene, η2-allyl, allene, vinyl, alkene, alkylidyne, η3-allyl, alkyne, N-heterocyclic carbene (NHC), and CCC pincer ligands, are discussed. Complexes with alkyl, cyclopentadienyl, acyl, iminoacyl, and related ligands are generally not discussed. Tantalum is among the largest early transition elements and can easily form complexes with high coordination numbers, although six is the most common. In addition, the larger radii of tantalum ions lead to less tight coordination sphere and frequently observed stereodynamic properties of the complexes. Tantalum complexes have been used as precursors to make electronic materials through processes such as chemical vapor deposition or atomic layer deposition. 

   more » « less
2. Enhancing Interconnect Reliability and Performance by Converting Tantalum to 2D Layered Tantalum Sulfide at Low Temperature

   https://doi.org/10.1002/adma.201902397  

   Lo, Chun‐Li ; Catalano, Massimo ; Khosravi, Ava ; Ge, Wanying ; Ji, Yujin ; Zemlyanov, Dmitry Y. ; Wang, Luhua ; Addou, Rafik ; Liu, Yuanyue ; Wallace, Robert M. ; et al ( June 2019 , Advanced Materials)

   The interconnect half‐pitch size will reach ≈20 nm in the coming sub‐5 nm technology node. Meanwhile, the TaN/Ta (barrier/liner) bilayer stack has to be >4 nm to ensure acceptable liner and diffusion barrier properties. Since TaN/Ta occupy a significant portion of the interconnect cross‐section and they are much more resistive than Cu, the effective conductance of an ultrascaled interconnect will be compromised by the thick bilayer. Therefore, 2D layered materials have been explored as diffusion barrier alternatives. However, many of the proposed 2D barriers are prepared at too high temperatures to be compatible with the back‐end‐of‐line (BEOL) technology. In addition, as important as the diffusion barrier properties, the liner properties of 2D materials must be evaluated, which has not yet been pursued. Here, a 2D layered tantalum sulfide (TaS_x) with ≈1.5 nm thickness is developed to replace the conventional TaN/Ta bilayer. The TaS_xultrathin film is industry‐friendly, BEOL‐compatible, and can be directly prepared on dielectrics. The results show superior barrier/liner properties of TaS_xcompared to the TaN/Ta bilayer. This single‐stack material, serving as both a liner and a barrier, will enable continued scaling of interconnects beyond 5 nm node.

    

   more » « less
3. Molecular beam epitaxy growth of superconducting tantalum germanide

   https://doi.org/10.1063/5.0189597  

   Strohbeen, Patrick J ; Banerjee, Tathagata ; Brook, Aurelia M ; Levy, Ido ; Sarney, Wendy L ; van_Dijk, Jechiel ; Orth, Hayden ; Mikalsen, Melissa ; Fatemi, Valla ; Shabani, Javad ( February 2024 , Applied Physics Letters)

   Developing alternative material platforms for use in superconductor–semiconductor hybrid structures is desirable due to limitations caused by intrinsic microwave losses present in commonly used III/V material systems. With the recent reports on tantalum superconducting qubits that show improvements over the Nb and Al counterparts, exploring Ta the superconductor in hybrid material systems is promising. Here, we study the growth of Ta on semiconducting Ge (001) substrates grown via molecular beam epitaxy. We show that at a growth temperature of 400 °C, the Ta diffuses into the Ge matrix in a self-limiting nature resulting in smooth and abrupt surfaces and interfaces with roughness on the order of 3–7 Å as measured by atomic force microscopy and x-ray reflectivity. The films are found to be a mixture of Ta5Ge3 and TaGe2 binary alloys and form a native oxide that seems to form a sharp interface with the underlying film. These films are superconducting with a TC∼1.8−2 K and HC⊥∼1.88 T, HC∥∼5.1 T. These results show this tantalum germanide film to be promising for future superconducting quantum information platforms.

    

   more » « less
4. Disentangling Losses in Tantalum Superconducting Circuits

   https://doi.org/10.1103/PhysRevX.13.041005  

   Crowley, Kevin D. ; McLellan, Russell A. ; Dutta, Aveek ; Shumiya, Nana ; Place, Alexander P. M. ; Le, Xuan Hoang ; Gang, Youqi ; Madhavan, Trisha ; Bland, Matthew P. ; Chang, Ray ; et al ( October 2023 , Physical Review X)
5. Tantalum sound velocity under shock compression

   https://doi.org/10.1063/1.5054332  

   Akin, Minta C. ; Nguyen, Jeffrey H. ; Beckwith, Martha A. ; Chau, Ricky ; Ambrose, W. Patrick ; Fat’yanov, Oleg V. ; Asimow, Paul D. ; Holmes, Neil C. ( April 2019 , Journal of Applied Physics)