Linnaeus Physics Colloquium: Scanning tunneling microscopy and photoemission studies of Ag films on metal/semiconductor surfaces
Välkommen till Linnaeus Physics Colloquium, en seminarieserie med framstående forskare i fysik.
Titel: Scanning tunneling microscopy and photoemission studies of Ag films on metal/semiconductor surfaces
Föreläsare: Samuel Starfelt, Institutionen för ingenjörsvetenskap och fysik, Karlstads universitet
Plats: Kalmar: sal Ma348, hus Magna. Live: https://lnu-se.zoom.us/j/416290322. Vi bjuder på kaffe och bullar.
Seminariet är en del av aktiviteterna inom kunskapsmiljön Avancerade material.
Metal-induced Si (and Ge)-√3×√3 surfaces offer two main benefits for growth of Ag films, compared to depositing directly on a semiconductor substrate. One advantage is the ability to grow films at room temperature, instead of using a two-step process including deposition at low temperature, which has been the standard for a long time. The other advantage is that for Si, the silver films grow as atomically uniform layers for thicknesses lower than 5 monolayers (the previous limit). For such thin films, the film/substrate interface will have a larger effect on the properties of the discrete quantum well states, which are formed by spatial confinement of electrons in the direction perpendicular to the surface. The presentation will cover both STM/STS and photoemission studies on Ag thin films on Ga, In and Sn-induced Si(111) (and Ge(111)) -√3×√3 surfaces. On the √3×√3 surfaces, the first layer of Ag forms a special interface, which facilitates layer-by-layer growth of Ag, even for thicknesses as low as 2 ML. The valence band electronic structures of the films show quantum well states, whose characteristics have been analyzed within the existing theoretical framework.