Regensburg 2025 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 26: Focus Session Ultrafast Electron Microscopy at the Space-Time Limit III
O 26.2: Vortrag
Dienstag, 18. März 2025, 11:00–11:15, H2
Steady-State and Time-Resolved Cathodoluminescence of III-Nitride Semiconductors — •Kagiso Loeto, Aidan Flynn Campbell, Domenik Spallelk, and Jonas Lähnemann — Paul-Drude-Institut für Festkörperelektronik, Berlin, Deutschland
Cathodoluminescence (CL), in steady-state and time-resolved modes, has advanced the study of semiconductor optical properties, crucial for microelectronics and III-nitride optoelectronics. A new state-of-the-art time-resolved CL (TRCL) microscope at the Paul-Drude-Institut features a high-performance SEM with a stable electron source and advanced light collection system, enabling optimized imaging and high spatial resolution at acceleration voltages as low as 0.35 kV. The system features a UV-optimized CCD camera for studying UV-emitting materials like III-nitrides. Time-resolved operation is enabled by an ultrafast beam blanker paired with detectors achieving temporal resolutions of tens of picoseconds, offering new insights into the dynamic optical properties of advanced semiconductors. It will be employed in three focus areas, highlighting its distinct capabilities. First, very-low acceleration voltage operation will enable high-resolution mapping of individual point defects in AlGaN quantum well structures, revealing their impact on AlGaN-based UV LEDs. Second, ultraviolet-optimized photon detectors will study temperature-stable excitonic bands in AlN with high spectral resolution, providing insights into their origins. Lastly, the instrument's time-resolved capabilities combined with spatial mapping will explore the interplay between carrier dynamics and localization in InGaN pseudosubstrates.
Keywords: Cathodoluminescence; Time-resolved cathodoluminescence; III-nitrides; Light-emitting diodes; Spectroscopy