Disputation: Vegard Skiftestad Olsen
Doctoral candidate Vegard Skiftestad Olsen at the Department of Physics, Faculty of Mathematics and Natural Sciences, is defending the thesis
"Functional Properties and Band Gap Engineering of ZnO-GaN Alloys"
for the degree of Philosophiae Doctor.
The University of Oslo is closed. Vegard's PhD defence will therefore be fully digital and streamed directly using Zoom. The host of the session will moderate the technicalities while the chair of the defence will moderate the disputation.
Ex auditorio questions: the chair of the defence will invite the audience to ask ex auditorio questions either written or oral. This can be requested by clicking 'Participants -> Raise hand'.
Contact Vegard, PhD, to request a copy of his thesis.
Conferral summary / Kreeringssammendrag
Dette arbeidet har vært fokusert på vekst og karakterisering av tynnfilmer, for bruk i optoelektroniske applikasjoner. Materialet, en legering av sinkoksid og galliumnitrid, har en sterk reduksjon i båndgap som funksjon av komposisjon. Et av hovedfokusene i denne avhandlingen har derfor vært å utforske mekanismene som styrer dette varierbare båndgapet.
Main research findings / Hovedfunn
Renewable energy sources play a vital role in handling the increasing energy demand, as well as the aim to reduce carbon emissions. New materials for solar cell applications are being developed for this sole reason. The ZnO-GaN (ZOGN) semiconductor alloys, consisting of two industrial well-proven materials with intriguing optical properties, have been found to yield tunable absorption from UV- and well in to the visible part of the solar spectrum, due to the so-called band bowing effect. The alloys have been developed and utilized for hydrogen production through overall water-splitting, and also show promising properties for optoelectronics. In this work, the fundamental properties of ZOGN alloys have been investigated with the aim of utilization in applications as solar cells, photo detectors and photo diodes.
Highly crystalline alloy thin films, grown using magnetron sputtering, have been investigated in terms of structural, optical and electrical properties. In particular, the mechanisms governing the band bowing effect observed in the materials have been explored, in order to understand and control the tunable absorption. This control is highly relevant for applications as solar cells, photo diodes and overall water-splitting.