Electronic structure information obtained with photoemission-based measurements provides a keystone in understanding emerging materials with potential applications in advanced semiconductor technology. This effort is focused on developing understanding of photoemission measurements of these materials and developing measurement advances to provide information in the time-domain and at nanoscale spatial dimensions.
Photoemission-based methods that interrogate solid state electronic structure have played a pivotal role in identifying and understanding key features of emerging materials. Band structure information from Angle-Resolved PhotoEmission Spectroscpy (ARPES) provided the first evidence for the d-wave symmetry in cuprate superconductors and the first illustration of Dirac character in graphene.
In this effort, measurements are being developed that push beyond the static band structure to provide a deeper understanding of the carrier dynamics in materials being considered for advanced semiconductor applications. Building on laser-based time-resolved techniques developed previously for investigating exciton dynamics photovoltaic materials these techniques can provide a picture of carrier dynamics that impact semiconductor device performance, particularly high-speed applications.
In addition, a need to push band structure measurements to nanoscale spatial dimensions arises, not only from increasingly small device dimensions, but also from the inherent heterogeneity of many materials. Many materials are characterized by coexistence of competing ferroelectric, magnetic, piezoelectric, etc. interactions, often leading to the formation of complex spatial phases, as in multiferroics with nanoscale dimensions. Measurement platforms that may address these issues are being considered.