In this interview, AZoMaterials speaks with Dr. Tamara Sloboda, Product Manager, and Dr. Marcus Lundwall, Head of Instrument Development for Industrial Applications, from Scienta Omicron about the non-destructive characterization of buried layer chemistry in semiconductors using HAXPES technology.
Can you please introduce yourself and your role at Scienta Omicron?
Dr. Tamara Sloboda: Certainly. I’m Dr. Tamara Sloboda, a Product Manager at Scienta Omicron. My background is in chemistry, with a Ph.D. from the KTH Royal Institute of Technology, where I focused on chemical and electronic properties of quantum dots and perovskite photovoltaics using synchrotron-based photoelectron spectroscopy.
At Scienta Omicron, I oversee the development of HAXPES and XPS solutions, ensuring they align with the evolving needs of the materials science community.
Dr. Marcus Lundwall: And I’m Dr. Marcus Lundwall, Head of Instrument Development for Industrial Applications. My Ph.D. in physics from Uppsala University centered around the structural characterization of nanoparticles using synchrotron electron spectroscopy.
Since joining Scienta Omicron in 2007, I’ve held various roles in R&D and business management, all focused on enhancing customer-focused instrumentation like our HAXPES lab systems.
Image Credit: goran gjorovski/Shutterstock.com
What makes HAXPES a valuable technique for investigating buried layers in semiconductors?
Dr. Tamara Sloboda: HAXPES, or Hard X-ray Photoelectron Spectroscopy, allows researchers to probe several tens of nanometers below the surface without damaging the sample. In semiconductors, where devices are made of numerous stacked layers, it’s critical to understand not only the surface but also the buried interfaces and sub-surface layers.
With higher photon energies, HAXPES achieves deeper penetration and greater escape depth of emitted electrons, enabling us to observe buried chemical states and layer composition—something traditional XPS cannot provide without sputtering.
How does HAXPES compare with traditional XPS when analyzing complex multi-layered devices?
Dr. Tamara Sloboda: XPS is inherently surface-sensitive, typically probing depths of about 5–10 nanometers. It’s excellent for surface analysis, but inadequate when we need to access buried interfaces.
HAXPES, using higher energy X-rays such as gallium K-alpha at 9.25 keV, can penetrate deeper—sometimes 50 nanometers or more—offering insight into the chemical states across multiple layers and at their interfaces. This means we can study devices like transistors or memory stacks in their intact form, gaining a comprehensive view of their buried layer chemistry without destructive preparation.
Can you provide an example where HAXPES revealed insights that traditional techniques could not?
Dr. Marcus Lundwall: Yes, one powerful example involved a solar cell structure where we compared three different ITO deposition methods. Using XPS, we had to sputter the surface to reach the SiO2 layer of interest, which can alter the chemistry due to ion beam damage. HAXPES enabled us to bypass sputtering and directly access the buried layer.
Surprisingly, HAXPES showed a completely different profile, revealing that the reactive product deposition method resulted in significantly more interfacial SiO2 than the other methods, contrary to what XPS suggested. This showed how non-destructive depth profiling can unveil true material states.
How does angle-resolved HAXPES contribute to depth profiling of semiconductors?
Dr. Marcus Lundwall: Angle-resolved HAXPES uses the fact that electrons emitted at different angles escape from different depths. Our wide-angle analyzer captures emissions across a 60° angular range simultaneously. With this, we can construct a non-destructive depth profile of the sample.
For instance, in a multilayered thin film with carbon, aluminum oxide, and titanium, we could clearly resolve the transitions between layers without any physical sectioning or sputtering. This 4D profiling approach adds an extra dimension of analytical power, helping researchers understand not just what’s present, but where it resides within the sample.
What role does HAXPES play in understanding ferroelectric materials like hafnium oxide?
Dr. Tamara Sloboda: Hafnium oxide-based ferroelectrics are promising for next-gen memory due to their ability to switch electric polarization states. But these thin films are sensitive to changes in oxygen vacancy distribution and interfacial chemistry.
Using HAXPES, we studied HZO films and observed differences in oxygen movement under applied electric fields. In polarized-up states, HAXPES revealed oxygen migrating toward the surface, changing the redox states at the interface. This movement wasn’t visible with surface techniques alone and underscores the importance of buried layer characterization in ferroelectric device behavior.
Could you explain how HAXPES enables operando studies in semiconductor stacks?
Dr. Marcus Lundwall: Operando HAXPES allows us to apply voltage while measuring electronic band structures in real time. One study involved an MOS structure, in which we observed how band bending changed under different bias voltages. By measuring shifts in the silicon 1s core level, we could map transitions from depletion to inversion or accumulation states.
This kind of analysis provides direct evidence of how electric fields affect buried semiconductor regions, enabling better design and tuning of devices for optimal performance.
How accessible is HAXPES for researchers without synchrotron access?
Dr. Tamara Sloboda: While HAXPES was once limited to synchrotrons, our HAXPES lab system brings this capability to standard labs. It combines a high-energy gallium X-ray source with a wide-angle electron analyzer, offering synchrotron-quality non-destructive depth profiling on the benchtop.
For those not ready to invest, we also offer HAXPES as a service—send us your samples, and we provide complete measurement and analysis. This flexibility opens the door to buried layer analysis for a much broader research community.
About Dr. Tamara Sloboda
Dr. Tamara Sloboda is a Product Manager at Scienta Omicron, specializing in surface science instrumentation with a focus on HAXPES and XPS systems. She holds a Ph.D. in Chemistry from the KTH Royal Institute of Technology, where her research focused on the chemical and electronic characterization of quantum dots and perovskite materials using synchrotron-based photoelectron spectroscopy.
At Scienta Omicron, she leads development efforts for high-end spectroscopy solutions, ensuring their alignment with the evolving demands of advanced material research. Her work bridges customer-focused innovation and technical excellence in spectroscopy applications.
About Dr. Marcus Lundwall
Dr. Marcus Lundwall is Director of Development for Industrial Applications at Scienta Omicron. He holds a PhD in Physics from Uppsala University, where his research focused on nanoparticle creation and characterization using synchrotron-based electron spectroscopy. Since joining Scienta Omicron in 2007, he has held senior roles in R&D and business management, contributing to key innovations such as the EW4000 analyzer and the monochromated 9.25 keV X-ray source for the HAXPES Lab system. He now leads the development of advanced instrumentation for industrial applications.
This information has been sourced, reviewed and adapted from materials provided by Scienta Omicron.
For more information on this source, please visit Scienta Omicron.
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