Sandia Labs FY21 LDRD Annual Report

FY21 ANNUAL REPORT

Next generation strategically radiation hard computing. Modern smartphones using state-of-the-art complementary metal oxide semiconductor (CMOS) can execute teraflops while consuming only a few watts. However, strategically radiation hardened (SRH) embedded CMOS technologies are constrained to much older technology nodes, with the most scaled SRH process technologies being about 150 nm (with 90 nm under development). This represents a gap of about seven generations between SRH and modern CMOS. (Modern CMOS has a performance advantage of 100 to 1000 times that of SRH CMOS.) Sandia’s Secure, Efficient, Extreme Computing (SEEEC) Grand Challenge project is addressing this performance gap by combining high performing SOTA CMOS with SRH CMOS. SEEEC integrated an SRH supervisor chip with advanced, high-performance commercially fabricated integrated circuits. This required the creation of a new modelling framework for the SEEEC architecture with a high-fidelity multi-scale model of radiation effects in modern scaled CMOS. Multiple radiation environments are under investigation; models are experimentally informed using test structures including single transistors, gates, larger blocks (e.g., arithmetic logic unit), full processor cores, and caches. SEEEC is providing a path to achieve state of the art computing performance in strategically radiation hard systems and has inspired a larger framework on advanced hybrid architectures. (PI: Matt Marinella) Fundamental mechanisms of friction evolution in lamellar solids. A variety of precision electromechanical devices in commercial aerospace and Sandia mission applications require critical solid lubricants because frictional performance changes during operation and storage in reactive atmospheres, thus restricting usage and limiting device designs. This LDRD project focused on understanding the atomic scale processes responsible for the evolution of friction coefficient in 2D lamellar materials. Recent research on molecular electronics motivated the first use of ‘work function’ to provide insights on atomic structure and defect content of worn surfaces and, with molecular dynamics simulations, showed that water increases the friction coefficient exhibited by MoS 2 (an exemplar lubricant) through disrupting the shear-induced restructuring of the surface into large, ordered

lamellae. Sandia partnered with Florida A&M- Florida State University’s College of Engineering, which developed a novel way to look at transfer films resulting from contact of lamellar solids. The resulting understanding will inform the design of tailored nanocomposites that suppress aging mechanisms and significantly improve reliability and performance of solid lubricants. (PI: Michael Dugger)

Work function (bottom) of MoS 2 wear tracks showing structure modification of surface lamellae (top left) due to environment. Atomistic simulations of MoS 2 (upper right) show water clustering at S vacancies.

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LABORATORY DIRECTED RESEARCH & DEVELOPMENT