Abstract
By using angle-resolved photoemission spectroscopy (ARPES), we measured successfully the electronic structure of low coverage (2×2) phases of indium thin films (~0.4ML) on flat Ge(100) surface and vicinal Ge(100) surface. We found several surface states crossing the Fermi level. We think in both systems surface states can be attributed to the hybridization between indium valence electrons and Germanium dangling bonds. The electronic structures of In/Ge(100)-(2×2) was simulated by first-principles calculation. Two different models have been investigated: the indium ad-dimers (i) parallel and (ii) orthogonal to the substrate Ge dimmers. To compare with measured results, the calculation based on In ad-dimers parallel to the Ge dimmers model is consistent with our ARPES result. By inspecting the 2D constant energy contours at Fermi level, we found interesting Fermi surface topology, the electron-like surface state bands seems different between indium deposited flat Ge(100) surface and indium deposited vicinal Ge(100) surface. The estimation of band width, kF, and electron density of surface states in In/Ge(100) and in In/Ge(100)- [011] 2.7° also agree with this discovery very well.