Abstract
Atomically uniform Pb films on Ge(001) were successfully pre-pared at the thickness ranging 4-16 monolayer above a wetting layer, Pb/Ge(001) – C(4X8) or mixture of C(4X8) and 3X6. Angle Resolved Photoemission (ARPES) and low energy electron diffraction (LEED) were used to study the system. We found the wetting layer is necessary to form the flat 2D Pb films. The measurement of the thickness depen-dence of the electronic structures for Pb films on Ge(001) was per-formed and the peak positions of quantum well states were analyzed by Bohr-Sommerfeld quantization rule. The measured peak positions match the theoretically predicted values very well. We also found that the line width of quantum well peaks become narrower within the energy range from -2 eV to -1 eV. It is due to the observed interesting behavior that quantum well state of Pb doesn’t interact with Ge heavy-hole (HH) bands. The thermal stability of Pb film was studied by annealing the Pb films and measuring the thermal stability temperature. The stability temperatures exhibited a bilayer oscillation. The annealing process rearranges the structure of Pb films. From the measurement by LEED, we discovered the trace of the cause to the resulting Pb(111) film rotated 15°with respect to the dimer direction of Ge(001) substrate.