System for angle-resolved photoelectron spectroscopy

• Subject Area: Condensed Matter Physics
• Term: Funded in 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 446792822

To enable research at the forefront on modern and emerging materials for electronics and optoelectronics, a system for angle-resolved photoelectron spectroscopy with high spatial resolution (µ-PES) should be acquired. Of particular interest in this research field is unraveling the chemical composition and electronic properties on all relevant length scales, down to the micrometer regime. The integrated ultrahigh vacuum system, comprising sample preparation and analysis chambers, facilitates sample fabrication/preparation under highly defined conditions, analyzing the surface structure by low energy electron diffraction (LEED), determining the surface stoichiometry with X-ray photoelectron spectroscopy (XPS), as well as investigating the electronic band structure with angle-resolved ultraviolet photoelectron spectroscopy (ARUPS). A key feature of the system is that XPS and ARUPS measurements can be performed from defined sample spots, where the microscopy function of the analyzer enables selecting areas as small as a few square-micrometers. This requirement is a consequence of the current and planned research program, which encompasses materials that are characterized by heterogeneity on the micrometer length scale. This pertains to two-dimensional (2D) materials, such as transition metal dichalcogenides, transition metal carbides and nitrides, as well as conjugated 2D polymers, all often in the monolayer form. Further components of the research program, i.e., intrinsic and doped organic semiconductors, also feature spatial variations that must be identified and distinguished in experiment. The overall aim of our efforts is obtaining a comprehensive understanding of these material classes' electronic properties, which significantly contributes to their evaluation for the use in novel electronic and optoelectronic devices. The system to be acquired substantially enhances the experimental capabilities, enables exploring new research fields, and enriches our present and planned cooperations.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: System für winkelaufgelöste Photoelektronenspektroskopie
• Instrumentation Group: 8310 UHV-Anlagen zur Analytik
• Applicant Institution: Humboldt-Universität zu Berlin
• Leader: Professor Dr. Norbert Koch