PhD - Leuven | About a week ago
QDs’ (Quantum Dots) optical properties are governed by their surface. Being of sizes of up to several hundreds of nanometers, the surface to volume ratio of these nanocrystals is very high. This means, a large portion of the atoms constituting the QD is actually found on their surface.
Since these atoms exist on the edge of the nanocrystal, they cannot be fully coordinated by their neighboring atoms and, therefore are very reactive to their surroundings.
When put into optoelectronic devices, QDs experience relatively high levels of heat, humidity, and light flux, and are exposed to external elements from the atmosphere or the surrounding matrix, such as oxygen, water, free radicals and free charges, passing through the QD layers. All these factors effect the chemical surrounding of the QD surface, and by doing so degrade its performance.
While a precise mechanism has yet to be universally accepted, it is clear that understanding of the degradation mechanisms of QD layer in optoelectronic devices is crucial in finding ways to improve the performance of this devices, in order to make them commercially useful.
The purpose of this PhD is to understand root cause(s) for QD
degradation mechanisms in an operational SWIR Thin Film Photodetectors, to
analytically assess the effect of these mechanisms and to come up with methods
of preventing them.
This PhD therefore has as goal to a) determine how and why QD based photodetectors degrades under different stress conditions and b) suggest alterations in the photodetector stack design or the QD chemistry to overcome these degradations. The PhD student will be involved in both the fabrication of the layers in our dedicated thin-film labs as well as in-depth characterization using microscopy tools (e.g., TEM/EDS, SEM, UPS and XPS), spectroscopy and analytical chemistry tools, in order to have a broad understanding of the chemical and physical processes at the QD film level
Required background: Chemistry, physics, device engineering
Type of work: 60% experimental 30% analysis and simulation 10% literature
Supervisor: Paul Heremans
Daily advisor: Itai Lieberman
The reference code for this position is 2021-100. Mention this reference code on your application form.