Electronic structure of Ge(111)c(2x8): STM, angle-resolved photoemission, and theory
2009 (English)In: PHYSICAL REVIEW B, ISSN 1098-0121, Vol. 79, no 20, 205410- p.Article in journal (Refereed) Published
The surface electronic structure of Ge(111)c(2x8) was studied by experimental techniques [low-energy electron diffraction, scanning tunneling microscopy (STM), and angle-resolved photoelectron spectroscopy (ARPES)] and theoretical band-structure calculations. Bias-dependent STM images exhibit two different types of adatoms (A(T),A(R)) and rest atoms (R-T,R-R) confirming the presence of asymmetries within the c(2x8) cell. The ARPES study resulted in a more detailed picture of the surface electronic structure of the Ge(111)c(2x8) surface compared to earlier studies. The energy dispersion curves showed the presence of seven surface bands labeled A1, A2, A2(), A3, A4, A4(), and A5. The experimental surface bands were compared to the calculated band structure of the full c(2x8) unit cell. The most important results are (i) we have identified a split surface-state band in the photoemission data that matches a split between R-T and R-R derived rest atom bands in the calculated surface band structure. This allows us to identify the upper A2 band with the R-R and the lower A2() band with the R-T rest atoms. (ii) The uppermost highly dispersive band (A1) originates from states below the adatom and rest atom layers and should not be confused with rest atom bands A2 and A2(). (iii) The bias-dependent changes in the adatom/rest atom contrast in the experimental STM images were closely reproduced by simulated STM images generated from the calculated electronic structure. (iv) A split was observed in the back-bond derived surface band at higher emission angles (A4 and A4()).
Place, publisher, year, edition, pages
2009. Vol. 79, no 20, 205410- p.
band theory, elemental semiconductors, germanium, low energy electron diffraction, photoelectron spectra, scanning tunnelling microscopy, surface states
IdentifiersURN: urn:nbn:se:liu:diva-19417DOI: 10.1103/PhysRevB.79.205410OAI: oai:DiVA.org:liu-19417DiVA: diva2:224932
Ivy Razado, Jiangping He, Hanmin Zhang, Göran Hansson and Roger Uhrberg, Electronic structure of Ge(111)c(2x8): STM, angle-resolved photoemission, and theory, 2009, PHYSICAL REVIEW B, (79), 20, 205410.
Copyright: American Physical Society