The doctoral dissertation in the field of Physics will be examined at the Faculty of Science, Forestry and Technology, Joensuu campus.
What is the topic of your doctoral research? Why is it important to study the topic?
My doctoral research focuses on developing ultrathin nanocarbon‑based terahertz (THz) components using pyrolytic carbon, pyrolyzed photoresist films, and fragmented graphene. These materials offer moderate conductivity, strong broadband THz absorption, and excellent impedance matching, enabling efficient THz interaction in films only tens of nanometers thick. This work is important because THz technology needs scalable, low‑cost, and CMOS‑compatible materials that outperform metals in absorption and integration.
What are the key findings or observations of your doctoral research?
My doctoral research shows that ultrathin nanocarbon films pyrolytic carbon, pyrolyzed photoresist films, and fragmented graphene can function as efficient, broadband THz absorbers and components. Despite being only tens of nanometers thick, these films exhibit strong Drude‑like THz absorption and impedance matching to free space, enabling significantly higher absorption than metals. I developed a direct CVD process for uniform PyC growth on fused silica and fabricated suspended PyC membranes and patterned PPF gratings with tunable THz responses.
The work demonstrates that low‑cost, scalable, CMOS‑compatible carbon films can replace metals in THz imaging, sensing, and filtering, and provides new insight into how disordered sp² networks interact with THz radiation, where local carrier dynamics not DC conductivity govern absorption.
How can the results of your doctoral research be utilised in practice?
My results enable low‑cost, ultrathin THz absorbers and filters made from scalable nanocarbon films. These materials can improve THz imaging, sensing, inspection, and wireless devices by offering lightweight, flexible, and CMOS‑compatible alternatives to metal‑based components.
What are the key research methods and materials used in your doctoral research?
My research involved synthesizing ultrathin nanocarbon films PyC, PPF, and fragmented graphene using CVD growth, photoresist pyrolysis, and transfer methods. I patterned membranes and fabricated gratings using lithography, then measured their terahertz response with THz time‑domain spectroscopy to understand absorption and conductivity.
The doctoral dissertation of Hamza Rehman, MSc, entitled Nanocarbon-based terahertz components will be examined at the Faculty of Science, Forestry and Technology, Joensuu campus. The opponent will be Professor Feodor Ogrin, University of Exeter, and the custos will be Professor Polina Kuzhir, University of Eastern Finland. Language of the public defence is English.
For further information, please contact:
MSc Hamza Rehman, [email protected], tel. +924 172 64700
