Pulsed laser deposition of c-axis oriented aluminum nitride thin films on silicon

Results on the deposition of aluminum nitride thin films on silicon (111) s ubstrates by pulsed laser deposition are reported. A KrF excimer laser was used to ablate in vacuum an AlN target. The intensity and the repetition ra te of the laser as well as the substrate temperature were varied and their effects on film properties were determined. The AlN films were characterize d by several techniques such as in situ laser interferometry, X-ray diffrac tion, X-ray photoelectron spectroscopy, atomic force microscopy and transmi ssion electron microscopy. At a deposition temperature of 500 degreesC and a laser intensity of 1 x 10(8) W/cm(2), highly oriented AlN layers are depo sited. Increasing the laser intensity leads to the presence of metallic Al in the films. As temperature is increased from 500 to 920 degreesC, the gro wth rate is found to decrease but the crystalline structure as well as the smoothness of the films are both significantly improved. It is also found t hat a reduction of the growth rate by varying the repetition rate from 30 t o 10 Hz leads to a further improvement of the crystalline quality of the Al N layers.