IBM Research - Almaden Science Colloquium Series - IBM Research Almaden ARC ANGELS Student Seminar Series
Science and Technology welcomes researchers from academia and industry to present their work in Almaden's Science Colloquium Series.
Science and Technology staff who are interested in inviting researchers for this series are encouraged to contact Gavin Jones (firstname.lastname@example.org) or Greg Wallraff (email@example.com) to arrange presentations.
Topic: Formation and Operation of Sustainable Energy Materials - Batteries and Solar Cells
Speaker: Mike Toney, Ph.D. (SLAC)
Date: 1/13/2016 Time: 10:30 AM - 11:00 AM
Location: Auditorium A
Abstract: To better understand how materials atomic structure affects their function, it is essential to observe this structure during operation – operando measurements. Similarly, to understand materials synthesis, we must be able to follow the transformation pathways during synthesis (in situ investigations). This talk will give an example of both - operando X-ray scattering of Si anodes and in situ X-ray scattering and spectroscopy of the formation of hybrid organic-inorganic halide perovskite (HOIP) films - unusual solar absorbers presently of considerable interest. First, we have used X-ray reflectivity to investigate the electrochemical lithiation of single crystalline silicon (100) electrodes, which allows us to gain nanoscale, mechanistic insight into the lithiation of Si and the formation of a solid electrolyte interphase (SEI) surface film on the Si anode. From this, we can determine the evolution of the lithiated Si (LixSi) layer and the SEI layer with sub-nanometer resolution. Second, we use in situ X-ray diffraction and spectroscopy to follow the temperature kinetics of HOIP composition and crystal formation, while the HOIP films are annealed after formation from solution. This provides insight into how HOIP formation processes.
Topic: Bridging the Opposite Worlds: Both Hyper-reactive and Stable Materials
Speaker: Prof. Sid Das (University of San Francisco)
Date: 2/3/2016 Time: 10:30 AM - 11:00 AM
Location: Auditorium A
Abstract: The design and facile synthetic route development of extremely reactive electro/photoactive materials that withstand degradation will be the focus of the talk. Our materials are (a) made using any element from the Periodic Table, (b) tuned at the atomic scale, (c) optimized to function at very fast rates (i.e. to be very reactive), and (d) made to be highly stable. This entails design and synthesis at the interface of the most energetically demanding redox reactions and fast kinetics, with the support of several spectroscopic characterization techniques (PXRD, UV-Vis, EPR, EXAFS, FTIR, TGA and AFM). This vision and methodology will enable us to overcome the core challenges in the major technological developments of the 21st century, such as batteries, solar cells, sensors and optoelectronics. Through a journey of molecular-materials by a chemist, the speaker hopes to demonstrate that freeing man-made materials from the compromise between the seemingly opposing worlds of reactivity and stability is not far-fetched and is essential for the progress of humanity in this and coming centuries.
Topic: New Strategies for Selective Deposition of Nanoscale Materials
Speaker: Prof. Stacey Bent (Stanford University)
Date: 4/14/2016 Time: 10:30 AM - 11:00 AM
Location: Auditorium A
Abstract: With the growing need for fabrication of nanostructures, selective deposition is likely to become an important process to achieve pattern features at the ~10 nm length scale. Both two-dimensional planar geometries and three-dimensional structures will benefit from selective deposition processes, with bottom-up growth strategies providing advantages in reduced process complexity and improved pattern fidelity. In this presentation, we will describe area selective deposition based on atomic layer deposition (ALD). ALD is a good choice for selective deposition because its chemical specificity provides a means to achieve selectivity on a spatially patterned substrate. Typically, in area selective ALD, self-assembled monolayers (SAMs) are used to passivate the surface, using SAMs in the regions where deposition is not desired. We will show that the process provides good selectivity for thin deposited films. However, a major challenge is that after a certain amount of material is deposited, the ALD process may begin to nucleate on the part of the surface covered with the SAM. We will describe new strategies to overcome the growth on the SAM and achieve significantly higher selectivity in area selective ALD. In one approach, to improve the blocking properties of the SAM on copper surfaces, the SAM is repaired between ALD cycles with the purpose of recovering the SAM’s properties. In a second approach, a “self-correcting” process is developed in which selective deposition is combined with selective etching, greatly improving the final selectivity. With both approaches, selective ALD of more than 60 nm of metal oxide dielectric material can be achieved. We also introduce a third strategy in which the substrate surface is modified by ion implantation of fluorocarbons, enabling topographically selective ALD. In this process, we demonstrate selective anisotropic deposition in which Pt deposition is inhibited on horizontal regions but active on vertical surfaces. Future directions in area selective ALD will also be discussed.