Spectromicroscopy and Microscopy of the Wide Bandgap Semiconductors GaN and SiC
2002 (English)Other (Other (popular science, discussion, etc.))
The research presented in this thesis concerns experimental studies of the surface properties of wide bandgap semiconductors GaN and SiC. GaN and some of the polytypes of SiC have important applications in blue and green emitting diodes.
In my work on GaN I show the effects of different surface treatments on the surface electronic structure, the surface chemical composition, and morphology. The objective of the different surface treatment methods was to produce a clean surface without destroying the surface electronic structure and original sample morphology. Some of the surface treatments used were sample heating in an ammoniac flux, deposition of gallium on the surface followed by desorption, and ion sputtering. Photoelectron spectroscopy and microscopy techniques were used to determine how the electronic and chemical structure changes, and atomic force and optical microscopy to image the surface. I have found that ammoniac flux anneal, and gallium deposition and desorption is conserving the surface electronic structure but do not removes all of the existing contaminations on the surface after the treatment, mainly carbon and oxygen. The ion sputtering seems to destroy the electronic structure on the surface, but remove the surface contaminations.
The SiC project was a study to determine the electronic structure of the hydrogenated 3C-SiC(001)-2ú1-H surface. This was done by exposing a SiC surface to excited hydrogen gas, forming a 2ú1-H surface reconstruction, and then study this surface by angle-resolved photoemission. The results also suggest a single Si monolayer termination on the 3C-SiC(001)-c(4ú2) surface.
Place, publisher, year, edition, pages
Karlstad: Karlstad University Studies , 2002.
IdentifiersURN: urn:nbn:se:kau:diva-23733ISBN: 91-85019-07-0OAI: oai:DiVA.org:kau-23733DiVA: diva2:597496