MSc Students Presentations - Drivas Charalampos

Presentation Title (Τίτλος Παρουσίασης): Determination of the chemical composition and electronic structure of oxide thin-films with applications in microelectronic devices by photoelectron spectroscopies
Presentation Type (Τύπος Παρουσίασης): MSc Students Presentations
Speakers Full Name (Ονοματεπώνυμο): Drivas Charalampos
Speakers Affiliation (Προέλευση Ομιλητή): Department of Chemical Engineering, University of Patras
Seminar Room (Αίθουσα): "A. C. Payatakes" Library
Event Date: Fri, Jun 29 2018, Time: 11:00 - 12:00
Abstract (Περίληψη)

Microelectronics is a continuously developing field, overcoming its limits every day. Its applications are numerous, ranging from high-tech devices to everyday ones, such as the smartphone, which reflects the rapid development of microelectronics the recent years. What’s more, state of the art arrays are used in solar cells to maximize their efficiency to provide sufficient sustainable energy. The trend nowadays is to make arrays as small as possible in order to fit as many of them in a device as possible. Hence, each layer constituting the array is getting smaller as well, up to the nanometer scale. This leads to surface phenomena being dominant and interfaces being “part” of the device.

In order to have a better insight to the properties of the surfaces and interfaces of common oxides used in such applications, the X-ray and Ultra-violet Photoelectron Spectroscopies (XPS and UPS respectively) were implemented as two complementary highly surface sensitive techniques. XPS provides information about the chemical composition of the sample’s surface from up to 10 nm in depth. UPS depth analysis is about 1-2 nm and it provides information about the electronic configuration of the surface.

First, a study has been carried out considering the Electron Extraction Layer (EEL) of organic solar cells upon doping with light and heavy metals in different nanostructures. Doping is a way to properly tune the desired properties, depending of the doping level, enabling the engineering of the EEL. More specifically, Li-doped ZnO films (0%, 2%, 5% and 10% Li) and Sn-doped ZnO (0%, 1%, 2% and 3% Sn) nanowires were studied by XPS and UPS, varying the doping levels. The doping of ZnO was confirmed by XPS and from the UP spectra, a slight variation of the Work Function (WF) of the Li-doped samples was detected, whereas for the Sn-doped ones further hybridization of the Zn orbitals was recorded upon doping.

For the second part, several interfaces between widely used ultra-thin oxide films (Al2O3, HfO2, ZrO2, Ta2O5 and ZnO) and oxide substrates (TiO2 and ZnO) were prepared by Atomic Layer Deposition (ALD). Such interfaces are used in organic solar cells as an addition layer between the EEL and the organic compound and in Metal-Oxide-Semiconductor-Field-Effect-Transistors (MOSFETs) as high-k dielectrics. They were studied by XPS, in order to investigate their possible interaction and the barriers imposed to the electrons and holes by the means of the Kraut et al. model.

Lastly, CoOx - promoted BiVO4 photocatalysts of variable Co content (0, 0.5 and 1.0 wt.%) were synthesized and studied by XPS in order to identify the chemical state of the CoOx and to calculate the Conduction and Valence Band offsets at the interface. The Co oxide was identified as Co3O4 and the offsets promoted separation of the electrons and holes, as desired. What’s more, it was shown that the Kraut et al. model, which is traditionally used for microelectronic devices, can be used in other applications, such as photocatalysis.

Speakers Short CV (Σύντομο Βιογραφικό Ομιλητή)


M.Sc. in Chemical Engineering

Department of Chemical Engineering - University of Patras, Patras (Greece)

Specialization in Materials Science and Technology

Master Thesis: Determination of the chemical composition and electronic structure of oxide thin-films with applications in microelectronic devices by photoelectron spectroscopies.

Supervisor: Professor S.Kennou (Surface Science Laboratory)


B.S. in Materials Science

Department of Materials Science - University of Patras, Patras (Greece)

First in the graduation order of the academic year​ 2015-2016. (8.06/10)

Bachelor Thesis: Synthesis and characterization of superconducting materials.

Supervisor: Professor P. Poulopoulos (Laboratory of High Tech Materials)

Honours and awards

·         Scholar of the 44th Regular Scholarship Programme for Postgraduate Studies of the Bodossaki Foundation.

·         Awards of excellence by the Limmat Foundation, Switzerland, Postgraduate Studies - Chemical Engineering - University of                 Patras.



·         Drivas, C., Kennou, S.
Interface Engineering of the Electron Extraction Layer in High Efficiency Polymer Solar Cells.
3rd Workshop of Graduates and Post-Docs in Chemical Engineering Sciences, Patras, Greece 4 October 2017 (oral presentation)

·         Drivas, C., Mpotzakaki, M.A., Georga, S.N., Krontiras, C.A., Kennou, S.
Synthesis of Ultra-thin Oxide Films Interfaces. Determination of their Chemical Composition and the Band Bending.
11th Panhellenic Chemical Engineering Conference, Thessaloniki, Greece 25-27 May 2017 (oral presentation)



[1].   Velegraki, G., Miao, J., Drivas, C., Liu, B., Kennou, S., & Armatas, G. S. (2018).
Fabrication of 3D Mesoporous Networks of Assembled CoO Nanoparticles for Efficient Photocatalytic Reduction of Aqueous Cr (VI).
Applied Catalysis B: Environmental, 221, 635-644.

[2].   Polydorou, E., Botzakaki, M. A., Sakellis, I., Soultati, A., Kaltzoglou, A., Papadopoulos, T. A., Briscoe, J., Drivas, C., … Vasilopoulou, M. (2017).
Improved Stability of Polymer Solar Cells in Ambient Air via Atomic Layer Deposition of Ultrathin Dielectric Layers.
Advanced Materials Interfaces, 1700231, 1–12.

[3].   Thu, C., Ehrenreich, P., Wong, K. K., Zimmermann, E., Wang, W., Fakharuddin, A., Putnik, M., Drivas, C., …                 Schmidt-Mende, L. (2018) 
Role of the Metal-Oxide Work Function on Photocurrent Generation in Hybrid Solar Cells.
Scientific Reports, 8, 3559.

[4].   Petala, A., Noe, A., Frontistis, Z., Drivas, C., Kennou, S., Mantzavinos, D., Kondarides, D.I. 
Synthesis and characterization of CoOx/BiVO4 photocatalysts for the degradation of propyl paraben. 
Journal of Hazardous Materials (in press)

[5].   ​​​​​​​Drivas, C., Botzakaki, M. A., Georga, S. N., Krontiras, C. A., & Kennou, S.
Heterostructures of metal oxides ultra-thin films. Determination of their band offsets and the chemical composition.
Materials Today: Proceedings (accepted)

[6].   Balis, N., Verykios, A., Soultati, A., Papadakis, Michael; Kournoutas, F., Drivas, C., ... Vasilopoulou, M.
Triazine-Substituted Zinc Porphyrin as an Electron Transport Interfacial Material for Efficiency Enhancement and Degradation Retardation in Planar Perovskite Solar Cells.
ACS Applied Energy Materials. (accepted)

[7].   Vamvasakis, I., Papadas, I.T., Tzanoudakis, T., Drivas, C., Choulis, S.A., Kennou, S., Armatas, G.S.
Exceptional Visible-Light Photocatalytic H 2 Production Activity of β -Ni (OH) 2 Modified CdS Mesoporous Nano-Heterojunction Networks.
ACS Catalysis (submitted)

[8].   Patsiouras, L., Skotadis, E., Gialama, N., Drivas, C., Kennou, S., Giannakopoulos, K., Tsoukalas, D.,
Atomic Layer Deposited Al2O3 thin films as humidity barrier coatings for Pt nanoparticle-based strain sensors.
ACS Applied Materials & Interfaces (submitted)

[9].   Polydorou, E., Botzakaki, M., Drivas, C., … Vasilopoulou, M.
Insights into the passivation effect of atomic layer deposited hafnium oxide for efficiency and stability enhancement in organic solar cells
Journal of Material Chemistry C. (submitted)