Year

Faculty/department - University/institution - Country

2011

Ph.D. in Condensed Matter Physics, Faculty of Physics, Bucharest University, Romania. Thesis title: „Gas sensing performance study on n-type (WO₃) and p-type (Cr₂O₃) semiconducting metal oxides”

2005

M.Sc. in Theoretical Physics and Condensed Matter, Faculty of Physics, Bucharest University, Romania

2003

Licence in Physics (Physical Engineer degree), Faculty of Physics, Bucharest University, Romania

I am a senior researcher at the National Institute of Materials Physics in Bucharest, Romania. I received my M.Sc. degree in Theoretical Physics and Condensed Matter from the Faculty of Physics-University of Bucharest in 2005 and Ph.D. in Physics in 2011 within the joint collaboration between the Gas Sensors Group at the National Institute of Materials Physics, Bucharest, Romania and Institute of Physical Chemistry, Tübingen University, Germany. My present work is focused on the understanding of gas sensing mechanisms with n and p-type semiconductor metal oxide-based (MOS) gas sensors up to ferroelectrics-like ceramics (e.g. ABO₃).

Related to the n-type MOS based gas sensors, I have been able to experimentally find that in the case of wolfram oxide (WO₃), the response to reducing gases, such as carbon monoxide (CO), is based on the interaction between the target gas and lattice oxygen, a phenomenon completely new to the way in which the interactions between CO and SnO₂ take place (e.g. interaction among CO and pre-adsorbed oxygen on species on the surface).

With regard to p-type oxidic semiconductor materials, it is worth highlighting my contribution expressed in the following two pillars, namely: the first is related to the way in which the CuO sensing performances are affected by the surrounding humidity level towards CO detection, whereas the second theoretically generalize the modelling of the overall p-type response towards reducing gases with respect to their morphology and intrinsic properties such as Debye length.

As an overall view, if one is looking at the equivalent circuit of the sensitive layer as a series of resistance circuit corresponding to the accumulation layer at the surface of the crystals (small as value) and of the volume (large), we can see that the resistance that changes, those of the surface layer, are the small ones and that the impact on the total resistance of the layer will be reduced. In the case of n-type conductive materials we encounter exactly the opposite situation because the resistors corresponding to the surface layer, in their case of depletion layer are much higher than resistors not affected by the surface effects with which they are in series.

One of the most interesting results obtained in the case of a p-type material is the link between the conductivity of the accumulation layer, which is proportional to the average concentration of holes. The consequence of the above is that the signal of a gas sensor made of a type p material, S_p, is smaller than that of a sensor made from a type n material, S_n, even under conditions where exposure to gases would cause the same variation in the curvature of energy bands at the surface (equally reactive materials), namely:

The challenges that arose during my research career were not limited to the materials listed above, but also to other systems studied: BaSrTiO₃ doped with Cu, Cr, La and Co, CeO₂:Mn₃O₄, SnO₂-CuWO₄, CuWO₄, ZnO-Eu₂O₃, etc which aroused my interest both in the development of realistic detection mechanisms in operating conditions similar to those found under in-field conditions. Currently my research is focused on both n-type and p-type MOS based sensors towards developing a gas detection mechanism using the formalism of quasi-chemical equations adapted to the gas sensing insights performances.

Over the time I was involved in the following international applications for fundraising and two invited talk as follows:

-          Joint Call 2018 on NOVEL TECHNOLOGIES, SOLUTIONS AND SYSTEMS TO REDUCE GREENHOUSE GAS EMISSIONS IN ANIMAL PRODUCTION SYSTEMS

Proposal title: Methane Diffusion Emission Acquisition system to reduce greenhouse gases and improve biogas energy efficiency (MEDEA)

Proposal ID: (see online application): 39664

-          Transnational Call 2019 – Manufacturing technology integration to develop a gas sensor demonstrator for medical application (MANUNET)

Proposal ID: MNET19/NMCS3700

-          Invited talk at the International Semiconductor Conference (CAS) 46^th Edition, 11-13 October, (2023), pg. 11-17, https://doi.org/10.1109/CAS59036.2023.10303715

-          Talk at the Department of Chemistry – University College London, UK – at the invitation of Prof. Chris Blackman, „Insights about sensing performance with n and p-type MOX based sensors” – 09.05.2019.