Low loss single crystalline aluminum films obtained on Si (111) through interfacial modulation

Single-crystalline aluminum (Al) films were grown on Si (111) substrates by molecular beam epitaxy to study the growth mechanism and demonstrate the role of interface modulation. The effect of the growth temperature is demonstrated on a series of 10 nm thick Al films, showing improved surface wetting by lowering growth temperatures. Post-annealing is proved to be effective on the elimination of twins within a thin Al film. The best twin-free Al film in this study was achieved by a two-step method, with a roughness less than 0.2 nm. The transmission electron microscopy results reveal the atomically sharp Al/Si interface. The ellipsometry measurements show an overall reduction on epsilon 2 compared to the Palik's values, and especially a more than 40% reduction is achieved in the UV regions.

Automated summary

Single-crystalline aluminum films were grown on Si substrates by molecular beam epitaxy to study the growth mechanism and demonstrate interface modulation. Lowering the growth temperature improved the surface wetting. Post-annealing effectively eliminated twins within a thin aluminum film. The best twin-free aluminum film with atomically sharp Al/Si interface was achieved using a two-step method. Ellipsometry measurements showed overall reduction in ε2 compared to Palik's values, especially in the UV regions.