Interface study of AlN grown on Si substrates by radio-frequency magnetron reactive sputtering

Wurzite AlN thin films have been grown on Si (111) and Si (100) substrates by using radio-frequency (RF) magnetron reactive sputtering. High-resolution transmission electron microscopy (HRTEM) revealed a thin (a few nanometers thick) disordered interlayer at the film/substrate interfaces on both surface orientations. Despite the transition layer, there was a preferential c-axis-oriented wurtzite AlN film on the substrates. The X-ray diffraction and transmission electron microscopy results also indicated that the AlN film had a columnar structure with the grains having the same crystallographic axis (0002) parallel to the substrate surface normal, but having randomly rotational orientations about that axis. Atomic force microscopy (AFM) measurements showed that the surface roughness is low, about 2.3 nm, and independent of the substrate used.