IMBB - WebCalendar

Time:

16:10

Description:

Speaker: Dr. Emmanouil Dimakis

Affiliation: Helmholtz-Zentrum Dresden-Rossendorf, Germany

Title: Extremely strained III-V semiconductor nanostructures

Location: Computer Science Department, room A115 (ground floor), Voutes

Time: 16:15 (sharp)

Language: English

Abstract:

Semiconductor materials have fuelled many technological breakthroughs over the last half century (wireless communication, computing, solid-state lighting, solar powering, etc.), leaving a monumental impact on our society. Switching, amplification and light-electricity (electricity-light) conversion are the most important functions they perform. The family of III-V compound semiconductors, in particular, is known for its high electron mobilities and direct band gaps. Most importantly, they are versatile materials due to the possibility to tailor their (opto)electronic properties by selecting their composition appropriately. When grown heteroepitaxially, though, this possibility is constrained by the lattice mismatch with the substrate.

The situation is significantly different in epitaxial nanostructures, where more possibilities for strain engineering are offered at the nanoscale and new physical phenomena with potential device applications can be explored. On the other hand, the growth of such nanostructures is very demanding and necessitates good understanding and precise control of the growth mechanisms. Two examples of extremely strained nanostructures will be presented in this talk. The first example concerns InN/GaN multiple quantum wells with a thickness of one monolayer each. The role of the “self-regulation mechanism” and the high lattice mismatch (11 %) in the successful growth will be highlighted, and the signatures of two-dimensional electron conductivity and its topological nature will be presented. The second example concerns vertical GaAs/InxGa1-xAs core/shell nanowires on Si substrates. This system consists of three lattice-mismatched materials, but the unique geometry of nanowires allows for growing them defect-free. The self-catalyzed vapor-liquid-solid growth mode, the peculiar accommodation of misfit strain, and the application of this type of nanowires in light emitting diodes and modulation-doped heterostructures will be discussed. The monolithic integration of GaAs/InxGa1-xAs core/shell nanowires in Si-CMOS platforms would have an enormous technological impact as high electron mobilities would boost the performance of transistors and composition-tunable direct bandgaps would add efficient optoelectronic functionalities (more-than-Moore).

Time:

16:10

Description:

Speaker: Dr. A. Papagiannopoulos

Affiliation: Institutes of Physical Chemistry, National Hellenic Research Foundation

Title: Nanostructured functional soft materials by self-organization of complexes between biological/synthetic macromolecules and bioactive compounds

Location: 3rd Floor Seminar Room (Physics Building)

Time: 16:15 (sharp)

Language: English

Abstract:

In the next decade the interactions between macromolecular components with proteins, drug molecules and genetic material will be exploited for the creation of novel functional nano-structures with advanced properties. Control of the organization of matter at the nano-scale is the key issue in modern applications of nano-medicine (drug-loaded nanoparticles), food science (enriched food matrices), tissue engineering (nanocomposite hydrogels) and biotechnology (protein separation). Macromolecular components offer versatile templates for creation of functional, stimuli-responsive and often bioactive systems via self-assembly. Modifications by physical self-assembly and temperature treatment is in cases preferred against chemical modification e.g. when the introduction of a chemically modified substance is a time consuming process. In a broader sense exploitation of physical interactions between natural components is a route to acceptable novel products. Small angle scattering methods and spatially sensitive measurements of viscoelasticity (i.e. microrheological techniques) are going to play central role in the imminent developments as they provide information at the relevant length scales. In this talk previous work on self-organization of synthetic and biological macromolecules, their interactions with proteins and the response of such systems to external stimuli will be presented. In more detail the role of electrostatic and hydrophobic interactions, the effect of thermal response and the hierarchical organization in synthetic, biological and hybrid aqueous solutions will be explored. The open questions in polymer/protein interactions will be illustrated and the potential of producing novel soft-materials by controlling these interactions will be presented.

Time:

12:00

Location:

“Seminar Room 1”, FORTH’s bldg

Description:

IMBB COLLOQUIUM

Konstantina KATSAROU
Kalantidis' Lab
Title: "Viroids: Infectious long non-coding RNAs"

Friday, April 287th 2017 @ 12:00
“Seminar Room 1”, FORTH’s bldg