Ternary Indium Gallium Nitride (InGaN) alloys posses a direct bandgap that can be tuned across the largest part of the solar spectrum (0.7 to 3.4 eV). Therefore, they are very promising candidates for the development of efficient solar cells. Towards this goal, a number of issues, related to epitaxial growth and phase separation phenomena, need to be addressed.
For photovoltaic applications, it is necessary to achieve thin films with high InN content (higher than 0.2 mol%), while controlling alloy homogeneity, which is challenging due to strong immiscibility of the binary constituents. Plasma assisted molecular beam epitaxy, in principle, can address this bottleneck, due to its metastable epitaxial growth character. However, the vastly different growth modes of GaN and InN, along with indium segregation and InGaN decomposition phenomena, complicate the epitaxial growth.
In this presentation, the investigations of growth kinetics of RF-MBE epitaxy of InGaN(0001) will be presented. For low growth temperatures, InGaN decomposition seems to be the dominant mechanism dictating the effective growth conditions. There are evidence that InGaN decomposition during growth is strongly influenced by surface phenomena and relates not only to the film composition and temperature but also to the adatoms arrival rate on the surface. For higher temperatures, when In desorption becomes more prominent, the conditions seem to be governed by the interplay of the two mechanisms.
The “growth window” leading to high quality epitaxial films of sufficient thickness, throughout the whole composition range, is identified. Furthermore, the influence of growth conditions, especially the growth temperature, on the occurrence of phase separation, as well as, on the different strain relaxation mechanisms involved (sequestration, introduction of threading dislocations and stacking faults and V-pits formation) will be discussed, along with the investigations of films’ optoelectronic properties.
Time:
12:00
Description:
Christiana Chatzimichail
«Genetic and Epigenetic regulatory networks in mouse Embryonic Stem Cells»
The backbone of the current microelectronics industry are components based on silicon semiconductors. However, the perspectives for further developments are limited due to material constraints like non availability for flexible devices, optical opacity and need for high temperature processing. The emerging class of oxide semiconductors is able to overcome many of those restrictions, especially because some of them can be prepared as thin (transparent) films under comparatively moderate conditions.
On the same line, functional oxides, with combination of properties, such as dynamic control of optical transparency and efficient light management, have been of increasing interest over the last decade.
Such coatings have opened up completely new applications areas such as smart windows, solar cell façades, etc., which can contribute significantly to reduce the global energy footprint of buildings and consequently the realization of green buildings.
In this presentation, after briefly introducing oxide-based functional materials, we shall focus on recent developments at MRG/IESL/FORTH on n-type and p-type oxides for optoelectronic applications as well as on chromogenic (thermo-electro-chromic) materials for smart windows and energy efficient buildings.
Time:
11:00
Location:
“Seminar Room 1”, FORTH’s bldg
Description:
IMBB SEMINAR
Bio-Rad’s Application Specialist
Title: "“Droplet Digital PCR technology”
1. Basic principles of ddPCR technology
2. Oncology applications
3. Gene editing application
4. Compare qPCR and ddPCR methods: pros and cons of each".