Electrical Resistivity & Thermal Stability of Smooth Silver Thin Film for Nanoscale Optoelectronic Devices

We discuss the electrical resistivity and thermal stability of smooth thin silver (Ag) films characterized by significantly lower root mean square (RMS) surface roughness, peak-to-valley height distribution, and grain-size distribution. The smooth film was prepared by using a very thin (_~1-2 nm) nucleation layer of evaporated germanium (Ge) prior to Ag evaporation. The sheet resistance of the rough silver (10 nm Ag) film is R_{Ag-rough ~}51 Omega/sq compared to the smooth silver (10 nm Ag/2 nm Ge) film with R_Ag.smooth ~22 Omega/sq. The smooth Ag is also shown to be thermally more stable for temperatures less than 120degC.