Nikolaos Kalfagiannis is interested in light-matter interactions and optical properties of materials and thin films both from experimental (spectroscopic ellipsometry) and computational point of view (finite-difference time-domain method).
– He is an expert in Spectroscopic Ellipsometry, a sophisticated optical technique that provides the complex refractive index of materials and thin films (in the latter case it also provides information about the thickness with Angstrom resolution). NTU is equipped with a unique IR Spectroscopic Ellipsometer (240–8000 cm-1 / 0.03 – 0.99 eV).
– Investigating the optical properties of nanostructured materials (plasmonics, phononics) and devices, employing the Finite Difference – Time Domain method with particular emphasis on IR photodetection.
– Fabrication of thin film materials via a range of physical and chemical vapour deposition techniques and solution processing methods (sol-gel).
– Exploring the self-assembly of noble metal layers into nanoparticles using laser processing. This method provides a new route to design predefined morphologies of surface and sub-surface nanoparticle arrangements with simplicity and versatility.
– Defect engineering and modulation of the optical and electronic properties of materials such as metal oxides, via Laser Annealing.

Light is pivotal in many chemical, biological and physiological processes but also underpins technologies of daily life: from smartphones to medical devices. At MTIF we have unique experimental capability to unveil the opto-electronic properties of materials via Spectroscopic Ellipsometry.

Dr Nikolaos Kalfagiannis

Current Research Areas & Activities

Metal-oxide perovskites as alternative low-loss infrared nanophotonic materials,
Defect engineering of transparent conductive oxides via Laser Annealing,
Materials’ doping via Laser Annealing,
Sol-gel metal-oxides for thin film electronics,
Developing and testing new capabilities for spectroscopic ellipsometry 

Specialises in

Opto-thermal properties simulation of laser processing.
Physics and technology of low dimensions
Laser Annealing

Spectroscopic Ellipsometry
Optical and electronic properties of materials
Computational electrodynamics (Finite-Difference Time-Domain method)

Defect engineering
Nanophotonics, plasmonics and phononics
Photonic applications and devices

Selected Publications

Embedded Metal Oxide Plasmonics Using Local Plasma Oxidation of AZO for Planar Metasurfaces. K. Sun, W. Xiao, S. Ye, N. Kalfagiannis, K. S. Kiang, C. H. Groot (Kees), Muskens, O. L. Muskens, Adv. Mater. 2020, 2001534.

3D-to-2D Morphology Manipulation of Sputter-Deposited Nanoscale Silver Films on Weakly Interacting Substrates via Selective Nitrogen Deployment for Multifunctional Metal Contacts. A. Jamnig, N. Pliatsikas, M. Konpan, J. Lu, T. Kehagias, A. N. Kotanidis, N. Kalfagiannis, D. V. Bellas, E. Lidorikis, J. Kovac, G. Abadias, I. Petrov, J. E. Greene, K. Sarakinos, ACS Appl. Nano Mater. 2020, 3, 4728-4738.

Mid- to Far- Infrared Sensing: SrTiO3, a Novel Optical Material. N. Kalfagiannis, J. L. Stoner, J. Hillier, I. Vangelidis, E. Lidorikis, J. Mater. Chem. C, 2019, 7, 7851–7857.

Conductive Nitrides: Growth Principles, Optical and Electronic Properties, and Their Perspectives in Photonics and Plasmonics. P. Patsalas, N. Kalfagiannis, S. Kassavetis, G. Abadias, D. V. Bellas, C. Lekka, E. Lidorikis, Mater. Sci. Eng. R Reports, 2018, 123, 1–55.

Recent Progress in Photonic Processing of Metal Oxide Transistors. E. Yarali, C. Koutsiaki, H. Faber, K. Tetzner, E. Yengel, P. Patsalas, N. Kalfagiannis, D. C. Koutsogeorgis and T. D. Anthopoulos, Adv. Funct. Mater. 2020, 30, 1906022.

Chapter 18: Laser Annealing as a Platform for Plasmonic Nanostructuring. N. Kalfagiannis, D. C. Koutsogeorgis, E. Lidorikis and P. Patsalas, in Nanoplasmonics – Fundamentals and Applications, 2017 (ISBN 978-953-51-3278-3).