The PhD defence and trial lecture will be streamed. The chair of the defence will moderate the disputation.
Ex auditorio questions: the chair of the defence will invite the audience physically present in the auditorium to ask ex auditorio questions.
→ Live streaming of trial lecture and disputation
→ Request for thesis copy (available until the disputation starts)
Trial lecture
Time and place: September 4, 2026 - 10:15 AM
Lille fysiske auditorium (V232) - Fysikkbygningen
Title: "The limits of doping in ultra-wide bandgap semiconductors: defect physics, compensation mechanisms, and device implications"
Main research findings
Discovering new materials is a crucial part of technological development. Semiconductors are a material class with especially high impact, and are essential for applications such as signal processing, sensors, and power conversion. Combinatorial materials science increases the efficiency of the search for new materials by making and investigating many materials at once, rather than the conventional one-by-one approach. The work presented herein focuses on samples made by Pulsed Laser Deposition (PLD), a synthesis technique that is especially well-suited for creating many different oxide samples at once.
This study addresses two aspects of materials science. First, efforts have been applied to improve the high-throughput workflow itself: optimization of how to prepare chemicals for use in combinatorial PLD, development of how to simultaneously grow samples at different temperatures, and investigations on how to improve the data quality of rapid measurements of combinatorial samples. Second, combinatorial PLD has been used to grow and investigate several Ga2O3 alloys. In addition to their scientific relevance, these wide- and ultra-wide bandgap semiconductors are of technological interest for energy generation and conversion, transparent conductive oxides, and solar-blind photodetectors.
Hovedfunn (Norwegian)
Å oppdage nye materialer er en viktig del av den teknologiske utviklingen. Halvledere er en materialklasse med spesielt høy relevans, og har utstrakte bruksområder innen blant annet signalbehandling, sensorer, og kraftomforming. Kombinatoriell materialvitenskap øker effektiviteten i søket etter nye materialer ved å fremstille og undersøke mange materialer samtidig. Dette arbeidet omhandler hovedsakelig prøver framstilt med pulserende laserdeponering (PLD), en synteseteknikk som er spesielt godt egnet for å lage mange oksidprøver samtidig.
De viktigste resultatene fra dette arbeidet kan deles inn i to kategorier. Den første innebærer metodeutvikling av kombinatoriell materialvitenskap: optimalisering av hvordan kjemikalier forberedes for bruk i kombinatoriell PLD, utvikling av en metode for vekst av prøver ved forskjellige temperaturer samtidig, og undersøkelser av hvordan man kan øke datakvaliteten i raske målinger av kombinatorielle prøver. Den andre innebærer syntese og undersøkelser av flere Ga2O3-legeringer. I tillegg til deres vitenskapelige relevans har disse halvlederne med brede og ultrabrede båndgap teknologisk betydning for anvendelser innen energiproduksjon, kraftelektronikk, gjennomsiktige ledende oksider, og solblinde fotodetektorer.
Adjudication Committee
- Associate Professor Karsten Fleischer, School of Physical Sciences, Dublin City University, Ireland
- Associate Professor Ingrid Gullikstad Hallsteinsen, Department of Materials Science and Engineering, Norwegian University of Science and Technology, Norway
- Associate Professor Alexey Koposov, Department of Chemistry, University of Oslo, Norway
Supervisors
- Professor Holger von Wenckstern, Department of Physics, University of Oslo, Norway / Felix Bloch Institute for Solid State Physics, Leipzig University, Germany
- Dr. Kristin Bergum, Department of Physics, University of Oslo, Norway / Institute for Energy Technology, Norway
- Dr. Athanasios Chatzitakis, Department of Chemistry, University of Oslo, Norway
- Dr. Kevin Gregor Both, Trafag AG, Switzerland
Chair of defence
Professor Anette Eleonora Gunnæs, Department of Physics, University of Oslo, Norway
Contact information to Department: Line Trosterud Resvold