Doctoral defense in physics - Arnar Már Viðarsson

Doctoral candidate: Arnar Már Viðarsson

Dissertation title: Detection of very fast interface traps at the SiC/insulator interface using different electrical characterization techniques

Opponents: Dr. Per Lundgren, professor at Chalmers University of Technology, Göteborg, Sweden. Dr. Philippe Godignon, professor at Universidad Autónoma de Barcelona, Spain.

Advisor: Dr. Einar Örn Sveinbjörnsson, Professor and head of Faculty of Physical Sciences, University of Iceland.

Also in the doctoral committee: Dr. Unnar Bjarni Arnalds, professor at the Faculty of Physical Sciences University of Iceland & Dr. Fredrik Allerstam, On Semiconductor, Kista, Sweden.

Chair of Ceremony: Dr. Birgir Hrafnkelsson, professor and vice head of Faculty of Physical Sciences.

Abstract

The main subject of this thesis is electrical analysis and characterization of very fast interface traps, noted as NI, at the interface between silicon carbide (SiC) and various dielectrics using different electrical analysis methods. Using metal-oxide-semiconductor (MOS) capacitors to characterize the SiC/dielectric interface by applying different electrical analysis methods at cryogenic temperatures we have observed defects that are present at the SiC/dielectric interface using three different dielectrics, these dielectrics being silicon dioxide (SiO2), aluminium nitride (AlN) and aluminium oxide (Al2O3). The NI trap can be observed using capacitance-voltage (CV) analysis and conductance spectroscopy at cryogenic temperatures. Post annealing SiO2 at high temperature in pure nitric oxide (NO) shows reduction in slower traps at the SiC/SiO2 interface but promotes the NI trap signal. However, using sodium enhanced oxidation (SEO) to grow the SiO2, significantly reduces the density of slower traps, and the NI trap are absent. AlN and Al2O3 show significant reduction in the density of slower traps compared to thermal SiO2, but the NI trap signal is clearly detected and has similar behaviour as in the NO annealed SiO2. The NI trap was first thought to be a defect within in the SiO2 dielectric, very close to the SiC conduction band edge. However, the presence of the NI trap in AlN and Al2O3 dielectrics suggests that the NI trap is on the SiC side of the SiC/dielectric interface and is not related to SiO2 as previously suggested.

About the doctoral candidate

Arnar Már Viðarsson got his BSc in physics from University of Iceland in 2014 and MSc in physics from University of Iceland in 2018 where he studied traps at the silicon carbide (SiC) and silicon dioxide (SiO2) interface. After graduation Arnar moved to Sweden to work for On Semiconductor as a test engineer in high power electronics. In January 2019 Arnar started his doctoral degree in physics at the University of Iceland under the where he has investigated electron traps at the interfaces between SiC and several different dielectrics for the last four years. His research has involved measurements of MOS capacitors with different electrical methods at cryogenic temperatures, analysis of traps and their effects of the quality of electrical components that can be fabricated with SiC.