[institut] Prezentacije u okviru Erasmus+ programa saradnje izmedju Univerziteta u Beogradu i Politehnickog univerziteta u Madridu

[Dusko Latas]

Poštovane koleginice i kolege,

Tokom sledeće nedelje na Fizičkom fakultetu i Institutu za fiziku biće 
održane prezentacije u okviru Erasmus+ programa saradnje između 
Univerziteta u Beogradu i Politehničkog univerziteta u Madridu, Španija, 
po sledećem rasporedu:

U utorak, 18. oktobar: Fizički fakultet, 12:00, sala 661, prezentacija 
programa i predavanje:
Nobel Prize winning materials changing the world: GaAs, GaN and graphene
Predavači: Dr. Jose María Ulloa, Dr. Žarko Gačević and Dr. Jorge Pedrós 
Institute for Systems based on Optoelectronics and Microtechnology 
(ISOM), Universidad Politecnica de Madrid

U sredu, 19. oktobar: Fizički fakultet, 11:00, sala 661, seminari:
Novel GaAs-based nanostructures for third generation solar cells,
predavač: Dr. Jose María Ulloa
GaN nanowires: from quantum light emitters to nanotransistors,
predavač: Dr. Žarko Gačević

U petak, 21. oktobar: Institut za fiziku u Beogradu, 14:00, čitaonica 
"dr Dragan Popović", SCL seminar:
Active plasmonics in graphene using surface acoustic waves, predavač:
Dr. Jorge Pedrós

U okviru ove saradnje, na raspolaganju su stipendije za razmenu za 
studente osnovnih, master i doktorskih studija, u trajanju od 6 meseci, 
tokom drugog semestra akademske 2016/2017. godine, kao i za razmenu 
nastavnog osoblja i istraživača. Dostupne mobilnosti u pozivu koji se 
zatvara 31. oktobra 2016. u 14:30 su:
-za nastavno osoblje i istraživače: jedna mobilnost od 30 dana i jedna 
od 15 dana, -za studente doktorskih studija: 4 studenta po 6 meseci, -za 
studente master studija: 9 studenata po 6 meseci, -za studente osnovnih 
studija: 4 studenta po 6 meseci.

Pozivamo sve zainteresovane studente, nastavnike i istraživače da 
prisustvuju navedenim prezentacijama i predavanjima.

U nastavku su apstrakti predavanja:

Nobel Prize winning materials changing the world: GaAs, GaN and graphene

Could Albert Einstein have ever imagined that his newly discovered 
phenomenon of stimulated emission would drive small and cheap 
solid-state light emitters allowing for world-wide optical networking?
What if Thomas Edison was told that in a very near future the light will 
be emitted from low-consumption displays consisting of billions of 
perfectly ordered solid state crystals? Would Paul Drude ever believe 
that virtually massless electrons will flow through solid-state devices 
enabling their ultra-high speed operation?
The science-fiction ultimately becomes reality thanks to materials such 
as GaAs, GaN and graphene. What is next? Nanostructure-based solar cells 
for clean energy harvesting? Single photon sources for quantum 
networking? 3D computers breaking Moore’s law limitations?
Supercapacitors enabling long-distance electric transportation?
Three young researchers working in the clean rooms of the Polytechnic 
University of Madrid will share their views on the past and future of 
the three Nobel-prize winning materials which are changing the world as 
we know it. They will encourage students to join their research 
conducted in highly competitive fields of nanotechnology, within the 
scope of Erasmus+ mobility.


Novel GaAs-based nanostructures for third generation solar cells

Third generation solar cells (SC) are being intensively investigated 
today as a main route towards high efficiency photovoltaics. Limitations 
in main approaches, such as multi-junction solar cells (MJSC) or 
intermediate band solar cells (IBSC) are nowadays due to the lack of 
materials and nanostructures with the required properties and band 
alignments. This is hindering the realization of MJSCs and IBSCs with 
the optimum designs. Today, GaAs-based epitaxy is starting to be mature 
enough to allow the design of complex nanostructure architectures with 
an unprecedented freedom. We propose a novel class of Sb-containing 
nanostructures based on GaAs that could lead to significant improvements 
in the development of third generation solar cells. Strain and band 
structure engineering strategies involving designs with different 
dimensionality will be discussed. In particular, lattice-matched 
GaAsSb/GaAsN type-II supperlattices are proposed as the optimum 
candidate to become the 1.0-1.15 eV layer in three- and four-junction 
SCs, while InAs/GaAs quantum dots with a modified thin (Al)GaAsSb 
capping layer could lead to enhanced single-junction SCs and IBSCs.

GaN nanowires: from quantum light emitters to nanotransistors

In the late 1990s several groups discovered that the growth of GaN with 
extraordinary crystal quality was possible on a variety of commercial 
substrates in the form of self-assembled nanowires, achieved via a 
simple catalyst-free growth method (bottom-up). While the catalyst-free 
approach enables an exceptional chemical purity, the high nanowire 
surface-to-volume ratio yields GaN nanowires with a virtually perfect 
crystal structure. This talk will summarize a recent progress in the 
fabrication of GaN nanowires and their employment in photonic and 
electronic nanodevices, such as quantum light emitters (single photon
sources) and field effect nanotransistors. The fabrication and 
characterization of single photon sources, relying on a pencil-like 
InGaN/GaN dot-in-a-wire structure will be presented. These sources emit 
linearly polarized single photons over a wide spectral range and are 
suitable for high-temperature operation. Their realization is an 
important step toward quantum communications. Next, the fabrication and 
characterization of a metal-semiconductor field effect transistor, 
relying on a GaN:Si nanowire will be given. The nanowires are processed 
horizontally, employing a semi-cylindrical top Ti/Au Schottky gate. The 
final NW-FETs (non-planar devices) are characterized by an improved 
channel electrostatic control. Their realization is an important step 
toward "3D computer" architectures. Finally, the performances of the 
hereby presented single photon sources and nanowire transistors are 
systematically compared to similar devices realized via different 
fabrication methods within the III-nitride material system.

Active plasmonics in graphene using surface acoustic waves

In comparison to conventional plasmonics, the tunability of graphene 
plasmons offers unique possibilities for applications in metamaterials, 
quantum optics control, biosensing, and light harvesting. However, most 
of the techniques developed so far for coupling light into graphene 
plasmons do not offer active control of the coupling mechanism. We have 
recently demonstrated a method to couple far-field radiation into 
propagating graphene plasmons by periodically deforming a continuous 
graphene sheet with an electrically generated surface acoustic wave 
(SAW). This mechanism allows to create a tunable optical grating without 
the need of any patterning in either the graphene layer or the 
substrate, thus eliminating edge scattering and fragility issues. An 
interdigital transducer (IDT) on a piezoelectric film is used to launch 
the SAW across the graphene sheet. By diffraction at the grating, 
incident laser light can overcome the momentum mismatch and excite 
propagating plasmons in the graphene sheet. This approach permits to 
efficiently control the graphene plasmons both temporally and spatially.
Thus, the propagating plasmons can be switched electrically via the 
high-frequency signal at the IDT and the generated plasmon wavefronts 
can be shaped by tailoring the IDT design.  Moreover, the IDT technology 
ensures the easy fabrication of graphene plasmonic devices by the 
microelectronics industry. In this talk, we will briefly review the 
different methods used so far for the generation of graphene plasmons, 
before presenting the details of our novel SAW-assisted approach. We 
will present the hybridized graphene plasmon-phonon dispersion in the 
graphene/piezoelectric structures, as well as the design and fabrication 
technology of the plasmonic devices, including the transfer of graphene 
to various piezoelectric materials. We will finally discuss different 
SAW-mediated plasmon functionalities based on several engineered device 
geometries.

Pozdrav,
Duško Latas