Teine Physicumi seminar toimub neljapäeval, 31. jaanuaril, kell 16.15 Physicumi ruumis B103. Physicumi seminar on uus seminariformaat, mis on mõeldud tasemelt kõigile kuulajatele, ning kus esinevad tippteadlased. Ettekande teeb Georg Pucker, PhD. Seekordne seminar toimub inglise keeles.
TITLE: Silicon Quantum Dots
ABSTRACT: Silicon quantum dots - often also called silicon nanocrystals - are attracting a lot of interest since the early work on light emission from porous silicon by L. Canham in UK and U. Gössele in Germany back in 1990. Silicon quantum dots embedded in a dielectric matrix can be seen as a more stable form of porous silicon maintaining the strong, typical red to near-infrared photoluminescence.
While the photoluminescence efficiency of silicon quantum dots can easily achieve some percent efficiency, electroluminescence is more difficult to obtain due to different barrier heights for holes and electrons and poor electrical transport. However, careful optimisation of growth parameters allows to control the average dimension of quantum dots and their distance. A study, in which Silicon quantum dots on top of a silicon solar cell were used will be presented. Indeed, an enhancement of the UV-blue efficiency and overall cell efficiency could be obtained. Finally, use of a Si-light emitting diode as light source in a compact quantum number generator will be presented as a potential application.
Image: Silicon wafer with hundreds of silicon quantum dot based light emitting diodes (LEDs), zoom on single LED, high resolution TEM image of silicon quantum dots.
SHORT BIOGRAPHY: Georg Pucker obtained his master's (1993) and doctor's degree (1996) in Technical Chemistry from the Technical University Graz – Austria, for his work in the field of optical spectroscopy of rare-earth doped glasses. From 1996 to 2000 he was a Post-Doc at the Department of Physics at the University of Trento, Italy, performing research in the field of optical spectroscopy of rare-earth ions and silicon nanostructures. In 2000 he joined ITC-IRST, now Bruno Kessler Foundation (FBK) in Italy. The R&D he is involved in ranges from research on organic and inorganic solar cells, radiation hard silicon detectors for particle tracking to thermo-electric devices. Since 2011, his research has focused on integrated photonics. He is author or co-author of over 90 publications in peer-reviewed journals, author of a book chapter and inventor of 4 patents.