Atomic Layer Deposition

Dr. Adriana SZEGHALMI

Wafer inspection in the clean room.

Image: Jan-Peter Kasper (University of Jena)
Wafer inspection in the clean room.
Adriana SZEGHALMI

Adriana SZEGHALMI

Image: Private

Dr. Adriana SZEGHALMI

Email: adriana.szeghalmi@iof.fraunhofer.de
Phone: +49 3641-9-47859

Dr. Szeghalmi leads the scientific group “Conformal Coatings” at the Fraunhofer Institute for Applied Optics and Precision Engineering IOF. Her research focuses on atomic layer deposition (ALD) and plasma-enhanced atomic layer deposition (PEALD) for optical coatings on complex, strongly curved, micro- and nanostructured components.

Research Areas

The research of Dr. Szeghalmi focuses on conformal optical coatings and the development of atomic layer deposition for demanding photonic applications. Research topics include:

  • Conformal optical coatings by ALD and PEALD
  • Antireflection coatings on strongly curved and complex optical surfaces
  • High-reflective coatings for high-power laser applications
  • Nanolaminates with tailored refractive index and optical properties
  • Coating and embedding of micro- and nanostructured optical elements
  • Nanoporous low-refractive-index materials
  • Optical coatings from the DUV to the NIR
  • Process development and optimization for oxide and nitride thin films

Teaching Fields

Dr. Szeghalmi supervises research projects and theses in the fields of:

  • Atomic layer deposition
  • Optical coatings
  • Thin-film materials
  • Surface functionalization and photonic nanostructures

The group is constantly offering topics and projects for Internships, Research Labs and Master theses that fit into the local Master curricula.

Research Methods

The group combines conformal thin-film deposition with detailed optical and structural characterization. Core methods include:

  • Thermal atomic layer deposition
  • Plasma-enhanced atomic layer deposition
  • Deposition of oxide and nitride thin films
  • Nanolaminate and multilayer fabrication
  • Spectrophotometry and spectroscopic ellipsometry
  • X-ray reflectometry and diffraction
  • Atomic force and electron microscopy
  • Thermal, chemical and environmental stability testing
  • Laser-induced damage characterization
Figure 1: Dispersion of TiO2 layers deposited (a) via plasma enhanced atomic layer deposition (PEALD), and (b) thermal atomic layer deposition (thermal ALD) at different deposition conditions. The plasma-enhanced atomic layer deposition of TiO2 was performed at different oxygen gas-flow rates, plasma powers and deposition temperatures TS. Thermal depositions were carried out at deposition temperatures of 120 °C, 150 °C and 200 °C. Refractive indices are based on the Cody-Lorentz model, chosen for its suitability to the obtained ellipsometric data.

Figure 1: Dispersion of TiO2 layers deposited (a) via plasma enhanced atomic layer deposition (PEALD), and (b) thermal atomic layer deposition (thermal ALD) at different deposition conditions. The plasma-enhanced atomic layer deposition of TiO2 was performed at different oxygen gas-flow rates, plasma powers and deposition temperatures TS. Thermal depositions were carried out at deposition temperatures of 120 °C, 150 °C and 200 °C. Refractive indices are based on the Cody-Lorentz model, chosen for its suitability to the obtained ellipsometric data.

Graphic: Szeghalmi research group.

Recent Research Results

Atomic layer deposition enables precise and conformal fabrication of optical thin films even on strongly curved surfaces and complex nanostructures. Recent work has demonstrated broadband and narrowband antireflection coatings on three-dimensional optical components, where conventional line-of-sight deposition techniques are limited. Conformal multilayer coatings on strongly curved optics achieved residual reflectances below 0.3% across the visible spectral range [1].

ALD is also increasingly used as a fabrication tool for nanophotonics and meta-optics. Atomically controlled dielectric coatings and heterostructures provide access to high-refractive-index materials and precisely defined nanoscale interfaces. Recent work demonstrated atomically thin metal–dielectric heterostructures and investigated their structural and optical properties as platforms for engineered light–matter interaction [2].

A further research direction addresses nonlinear optical functionality. Metal–dielectric heterostructures fabricated by ALD have been investigated for second-harmonic generation, demonstrating that nanoscale layer architecture can be used to tailor nonlinear optical responses [3].

The group also contributes ALD processes for dielectric metasurfaces and meta-optics in demanding spectral regions. Recent developments include hafnium-oxide-based structures for ultraviolet meta-optics and ALD-functionalized metasurfaces for dynamically and spectrally engineered optical responses [4,5].

[1] Gerold et al., Appl. Opt. 62, B92 (2023).
[2] Paul et al., ACS Appl. Mater. Interfaces 15, 22626 (2023).
[3] Paul et al., Opt. Mater. Express 15, 1236 (2025).
[4] Siefke et al., EPJ Web Conf. 335, 08003 (2025).
[5] Walden et al., ACS Nano 18, 5079 (2024).

Link to the Szeghalmi group at Fraunhofer IOFExternal link