| AVS 55th International Symposium & Exhibition | |
| Surface Science | Wednesday Sessions |
| Session SS2-WeA |
| Session: | Electrons and Electronic Spectra at Surfaces |
| Presenter: | J.D. Kim, The University of Texas at Austin |
| Authors: | J.D. Kim, The University of Texas at Austin S.Y. Qin, The University of Texas at Austin C.K. Shih, The University of Texas at Austin |
| Correspondent: | Click to Email |
The thickness dependence of tunneling decay constant (κ) for ultra thin Pb films is studied with various sample biases by using low temperature STM. It is found that quantum well states (QWS) have a strong influence on κ. While the decay constant versus layer thickness (κ vs. L) clearly shows bilayer oscillations, we found that the apparent contrast in κ vs. L also show strong bias dependence. This result shows that κ-oscillation does not necessarily imply the work function oscillation. We further show that in this case, the parallel component of crystal momentum plays a critical role in tunneling process and is largely responsible for the observed phenomena. On the other hand, at large negative sample bias, the measured decay constants shows less bias dependent. Nevertheless, at small negative biases (less than 0.3 V below), the measured κ is strongly influenced by location of QWS near Fermi energy.
1NSF-IGERT DGE-0549417; NSF-FRG 26-1126-8750.