| AVS 55th International Symposium & Exhibition | |
| Surface Science | Wednesday Sessions |
| Session SS1+NC-WeM |
| Session: | Surface Structure and Morphology |
| Presenter: | J.S. Lee, University of California, San Diego |
| Authors: | J.S. Lee, University of California, San Diego E. Chagarov, University of California, San Diego A.C. Kummel, University of California, San Diego |
| Correspondent: | Click to Email |
Several recent reports on Ge MOSFET have shown the benefit of having either GeON or GeN interfacial layer between Ge and the high-k gate oxide. We have performed scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) experiments to understand the bonding and electronic structure for Ge-O and Ge-N surface species. For Ge-O, a Ge(100) surface was exposed to O2 and annealed to form order structures. The O2 dosing pins the Fermi level at high local coverage. Formation of Ge-N adsorbates is more challenging since N2 nor NH3 readily dissociate on clean Ge(100). We performed the direct nitridation on Ge(100) using an electron cyclotron resonance plasma source, and investigated the submonolayer structures of the surface using STM. The nitrided surface was annealed between 200°C and 500°C to differentiate the various adsorbate sites. By annealing the surface above the oxygen desorption temperature but below the nitrogen desorption temperature, our preliminary data is consistent with our being able to prepare Ge-N adsorbates. We are also performing STM experiments and DFT calculation to determine the electronic structure of the Ge-N adsorbates and explain why they might be superior interfacial passivants compared to pure GeO2.