I am seeking a post-doctoral researcher to augment our current research, which concentrates on new approaches to extending optical capabilities for the characterization of nanoscale devices as they increase in complexity, with challenging new materials properties, thicknesses, and length scales that defy simplistic applications of the fundamental equations of electromagnetism. Two main thrusts are listed below:
Optically Measuring Near-Atomic Features of Nanoscale Devices - Due to the thickness dependence of the dielectric function (DF) below 5 nm and its effects upon the fundamental behavior of light reflecting and scattering off ultrathin films and structures, measurement science is to be advanced by developing in tandem atomic-scale ab initio DF calculations and experimental methods that capture predicted changes, improving one’s physics-based modeling beyond what is currently available. We seek to expand optics-based measurement science not only to the end of the nanoscale device “roadmap” below 3 nm in critical dimension but to develop the underlying enabling characterization technologies over large areas for QIS-fostering elements such as two-dimensional materials and atom-based devices. We are augmenting our well-recognized existing competency in electromagnetic simulation with a competency in modelling through density-functional theory (DFT) the band structures that determine the macroscopic dielectric function (e). Improving optical physics-based modeling at thickness, d, requires accurate use of Maxwell’s Equations with proper e(d) which for 2D materials is a tensor. While multitudes of scientists use DFT, and many employ electromagnetic (E&M) codes, few pair these together. We will also extend our measurements over larger areas. In addition to DFT experience and E&M expertise, our novelty as shown in a recent paper (J. Power Sources, 364 (2017) 130) is that we can experimentally image over 400 um2 areas using our high-magnification platform and also detect over 100 mm2 areas using a custom-built reflectometer with a 12-mm diameter beam.
Quantitative Nanoscale Imaging through Artificial Intelligence - As the electromagnetic modelling undergirding key industrial nanoscale measurements grows ever more complex with some adopting physics-free machine learning (ML), measurement strategies are to be developed to harness the potential of ML while both validating accuracy and uncertainty and enabling the integration of physics-based a priori information. We are developing quantitative approaches for interpreting optical scattering and imaging of nanoscale devices though the use of machine learning (ML). From the literature, nanoscale device characterization is already being performed in manufacturing using physics-free, algorithmic approaches with reports of improved uncertainty. None of these reports however make clear how accuracy is achieved nor what relationship exists between their uncertainty and accepted uncertainties as defined in the Guide to Uncertainty in Measurement (GUM). The goal is also pursued through the development of advanced ML for the detection and potential identification of patterned and unpatterned defects.
Areas of expertise that would be of great benefit include the following:
About Postdoctoral Opportunities at the National Institute of Standards and Technology
The National Institute of Standards and Technology (NIST) MISSIONTo promote U.S. innovation and industrial competitiveness by advancing measurement science, standards, and technology in ways that enhance economic security and improve our quality of life.The Physical Measurement Laboratory (PML) sets the definitive U.S. standards for nearly every kind of measurement employed in commerce and research, and is a world leader in the science of measurement. PML relies on outstanding postdoctoral research associates to aid in those efforts