BrainMap

Mr. Stefan Antohe

Prof. univ. Dr.

Professor - UNIVERSITATEA BUCURESTI

Researcher | Teaching staff | Scientific reviewer | Manager

Web of Science ResearcherID: C-4954-2011

Expertise & keywords

Multilayered Photovoltaic Structures for Space Applications Call name: Joint Applied Research Projects - PCCA 2013 - call
PN-II-PT-PCCA-2013-4-0776 2014 - 2017

Role in this project:

Coordinating institution: UNIVERSITATEA BUCURESTI

Project partners: UNIVERSITATEA BUCURESTI (RO); INSTITUTUL NATIONAL DE CERCETARE - DEZVOLTARE PENTRU FIZICA MATERIALELOR BUCURESTI RA (RO); INSTITUTUL NATIONAL DE CERCETARE - DEZVOLTARE PENTRU FIZICA SI INGINERIE NUCLEARA " HORIA HULUBEI " - IFIN - HH (RO); MGM STAR CONSTRUCT S.R.L. (RO)

Affiliation: UNIVERSITATEA BUCURESTI (RO)

Project website: http://mdeo.eu/MDEO/Proiecte/PN288-2014/

Abstract:

Thin film based PV structures are well fitted for space technology, due to their reduced mass. This proposal aims at investigating technological routes for fabricating thin film based multiple junction photovoltaic (PV) structures of the type ZnS/ZnSe/CdTe in superstrate configurations and to study their endurance to energetic (2-10 MeV) protons and alpha particles, which are the main components of cosmic rays, at 10^10 - 10^14 cm^-2 fluencies. In the superstrate configuration one starts with depositing the transparent front-electrode onto the glass substrate which supports the entire structure, and then, on top of it the ZnS, ZnSe, CdTe layers and finally the back-electrode. The efficiencies of the cells in superstrate configurations will be characterized, and also their endurance to irradiation. Special attention will be paid to the physical properties and the electrical response of the back-contact metal/CdTe. CdTe, an excellent photon absorber with a forbidden gap of 1.4 eV and a large light absorption coefficient, is known as a “difficult” semiconductor: due to its rather large work function, a special care must be taken to prepare a quasi-ohmic low-resistance contact with a metal. Ion implantation will be used to control electrical properties of CdTe layer, by doping with properly selected electrically active impurities. A special attention will be paid to the quality of interfaces; an optimization of the PV structures will be performed. The nature of the defects introduced by irradiation will be studied and their influence on the performance of the structures will be indicated.

High efficiency electrospinning Call name: Joint Applied Research Projects - PCCA-2011 call, Type 2
PN-II-PT-PCCA-2011-3.2-1017 2012 - 2016

Role in this project:

Coordinating institution: INSTITUTUL NATIONAL DE CERCETARE - DEZVOLTARE PENTRU FIZICA MATERIALELOR BUCURESTI RA

Project partners: INSTITUTUL NATIONAL DE CERCETARE - DEZVOLTARE PENTRU FIZICA MATERIALELOR BUCURESTI RA (RO); INSTITUTUL NATIONAL DE CERCETARE DEZVOLTARE PENTRU FIZICA LASERILOR, PLASMEI SI RADIATIEI - INFLPR RA (RO); UNIVERSITATEA TEHNICĂ "GHEORGHE ASACHI" IAŞI (RO); UNIVERSITATEA BUCURESTI (RO); ADINA S.R.L. (RO)

Affiliation: UNIVERSITATEA BUCURESTI (RO)

Project website: http://www.infim.ro/projects/high-efficiency-electrospinning

Abstract:

The main objective of the project is to develop a highly efficient alternative of the electrospinning method for preparing polymer nanofibers. The fabrication process we develop aims at using, instead of the classical spinnerets (syringes and pipettes), arrays of metallic micronic and submicronic tubules.

Secondary objectives will be the fabrication of functional metallic fibers, fabrics and products based on it for shielding applications and of complex fibers and fabrics for photovoltaic applications.

The process of electrospinning has numerous advantages. Properties of the fibers can be well controlled. The fibers are very thin and have a high length to diameter ratio, thereby providing a very large surface area per mass unit. A wide range of polymers can be processed in this manner including here natural polymers such as collagen, fibrinogen or polysaccharides. Is a method that allows one to deposit very thin polymer fibers, diameter down to few tens of nanometers.

Although the process is studied since long time ago, a scan through recent scientific literature presents the main shortcoming of the method, the low yield in terms of quantity of material produced.

Thus, the consortium approaches a problem of high technical and scientific interest, namely to develop an alternative to the method in order to increase the efficiency of nanofiber fabrication through electrospinning. We aim at replacing the classic syringe needle, pipette or other capillary with an array of metallic micrometer or submicrometer tubules prepared by a template approach.

The main objective of the groups involved in the present project is related to making the transition from the simple preparation of nanostructures towards fabricating functional nanostructures , namely of polymer, metallic and complex semiconducting fibers with high application potential. The research which will be performed is channeled in a direction strongly connected to the tendencies at international scale.

Advanced many-body spin transport and spin relaxation phenomena in nanowire systems Call name: Postdoctoral Research Projects - PD-2011 call
PN-II-RU-PD-2011-3-0044 2011 - 2013

Role in this project:

Coordinating institution: Universitatea din Bucuresti

Project partners: Universitatea din Bucuresti (RO)

Affiliation:

Project website: http://solid.fizica.unibuc.ro/~nemnes/PD/index.html

Abstract:

During the past few years spintronics has become one of the leading trends in semiconductor nanotechnology, especially due to its potential application in quantum computing. Although the prototypical spin field effect transistor (spin-FET) was first proposed by Datta and Das in 1990, the experimental realization has met serious challenges, the most important being the control and tunability of the Rashba spin-orbit coupling and efficient spin injection. However, recently, new advances which allow few modes conduction in nanowires and novel materials have boosted the performances of the spin-FETs and spin filters. Within this project, issues related to the coupling of spin-orbit interaction in the presence of magnetic impurities, many-body effects such as spin Coulomb drag and magnetic properties of nanowires made of diluted magnetic semiconductors, including the spin dynamics, will be addressed. The methodology used lies in the path of expertise of the project leader: coherent wavefunction formalism based on the R-matrix method, atomistic description using the density functional theory, spin transport using non-equilibrium Green's function and adaptative methods for the description of spin dynamics. The project will certainly enhance the understanding of many-body phenomena in spin transport,

bring forward new developments in the search for performant diluted magnetic semiconductors and provide efficient techniques for spin relaxation phenomena.

FILE DESCRIPTION	DOCUMENT
List of research grants as project coordinator or partner team leader
Significant R&D projects for enterprises, as project manager
R&D activities in enterprises
Peer-review activity for international programs/projects