Correlative Analytical Workflow with STEM-CL and EDS for Photovoltaic and Optoelectronic Devices
Cathodoluminescence (CL) spectroscopy in the scanning transmission electron microscope (STEM) enables direct nanoscale mapping of band gaps and defect-induced sub-band-gap states, providing unique insight into the optoelectronic properties of photovoltaic and optoelectronic devices.
In this webinar we present a correlative microscopy workflow that combines SEM-CL, FIB-SEM and STEM-CL. Using CdTe-based photovoltaic thin films and InGaN-on-Si LEDs, we will discuss practical considerations for optimizing STEM-CL experiments, including FIB specimen preparation with a range of ion species, the influence of specimen thickness, and the role of cryogenic cooling in maximising CL signal quality and spatial resolution.
We will demonstrate how STEM-CL analysis delivers nanoscale band-gap mapping, complementary to HAADF imaging and EDS, revealing how defects and alloying elements influence local band-gap variations and device performance.
The webinar will also introduce the instrumentation used throughout the workflow, including a Thermo Fisher Scientific Xenon Helios G4 plasma FIB equipped with a Gatan Monarc-Pro CL system for SEM-CL and TEM lamella preparation, and a Talos F200i STEM fitted with an Attolight Mönch CL detector and a Mel-Build liquid-nitrogen holder for STEM-CL measurements.
Figure 1. (a) STEM EDS map, (b) CL map of the direct band gap, (c) CL intensity at 1.367±0.05eV and (d) the corresponding spectra in a Se alloyed CdTe thin film doped with As.
Speakers
Arno Meingast
Dr. Meingast is Business Development Manager TEM. He has more than 15 years of experience in TEM in industrial and academic surroundings. He obtained his PhD at the Technical University of Graz where he focused on analytical techniques such as EDS and EELS. After that he moved to Sweden where he continued this focus working for several years as senior TEM scientist in industry. Thereafter he worked for six years as senior applications specialist in the European demonstration lab of Thermo Fisher Scientific (NanoPort) in Eindhoven.
Stuart Robertson
Drs Stuart Robertson and Zhaoxia Zhou both are Senior Research Fellows at the Loughborough Materials Characterisation Centre (LMCC), Department of Materials, Loughborough University. Dr Robertson is the FIB specialist and Dr Zhou specialising in TEM. Together they provide materials characterisation solution including cathodoluminescence (CL) to academic researchers and local businesses. LMCC hosts the national facility for high resolution CL analysis, which is open to users from both academia and industry across a wide range of application areas.
Zhaoxia Zhou
Drs Stuart Robertson and Zhaoxia Zhou both are Senior Research Fellows at the Loughborough Materials Characterisation Centre (LMCC), Department of Materials, Loughborough University. Dr Robertson is the FIB specialist and Dr Zhou specialising in TEM. Together they provide materials characterisation solution including cathodoluminescence (CL) to academic researchers and local businesses. LMCC hosts the national facility for high resolution CL analysis, which is open to users from both academia and industry across a wide range of application areas.
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