Quantum well dimension and energy level determination in Pb/Si(1 1 1)-7×7

The comparison between measured vs calculated electronic energy levels in quantum well states (QWS) depends on the dimension of the potential well confining the electrons. The dimensions of the well can be determined with structural probes (high resolution LEED and STM) while the electronic structure can be obtained with angle resolved photoemission and STM spectroscopy. For heteroepitaxial growth the dimension of the well depends on the thickness of the wetting layer between the island and the substrate. For the Pb/Si(1 1 1)-7 × 7 system using SPA-LEED and STM, we have measured the thickness of the layer underneath the islands and the substrate to be 1 ML at all temperatures. For Pb films grown on top of the Si(1 1 1)-7 × 7 at low temperatures T<110 K we have determined the height distribution at the metal/vacuum interface with STM to test how the quantitative analysis of QWS found in photoemission experiments is affected.