Electroreflectance of silver in smooth and microstructured tunnel junctions

摘要

Measurements of the electroreflectance (ER) of smooth and microstructured Ag surfaces have been performed with use of Al‐Al2O3‐Ag tunnel junctions at room temperature. The ER spectra of smooth silver are found to be in excellent agreement with those reported earlier by Kolb and Kotz Surf. Sci.24, 417 (1971) in electrochemical cells. A dip athngr;=3.78 eV can be seen forppolarization and a peak appears athngr;=2.94 eV due to the surface plasmon excited at the Al‐Al2O3interface. In the microstructured junctions the very high field (∼1010V/cm) present at the top of the Ag posts induces a shift of the maximum at 3.9 eV forppolarization and a large negative signal in the 3–4 eV range which cannot be observed in the conventional ER experiments. The free‐electronlike theory of the ERs does not account for these experimental data.