Growth of a highly c-axis oriented AlN thin films

The realization of AlN thin films, mainly oriented along (002) direction, is an important achievement for their integration in piezoelectric devices. This work reports structural properties of predominantly c-axis oriented AlN... [ view full abstract ]

The realization of AlN thin films, mainly oriented along (002) direction, is an important achievement for their integration in piezoelectric devices. This work reports structural properties of predominantly c-axis oriented AlN thin films. The studied films were grown on semiconductor seed layer using sputtering DC magnetron method.

After the growth process, film crystallinity quality of the resulting products was probed by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Raman spectroscope (HORIBA JobinYvonLabRAM) with a He-Ne laser excitation wavelength of 633. A surface morphology and roughness were studied by atomic force microscopy (AFM). In addition, the optical properties of the AlN films were studied using a Varian Cary-500 spectrophotometer.

Microscopy analysis showed that the DC magnetron films displayed a uniform surface without any micro-cracks. The cross-section SEM images revealed that the AlN films consist of oriented columnar grains that are perpendicular to the surface of the Si substrates. The XRD patterns showed the formation of the polycrystalline phase of AlN where (100), (002) and (101) peaks appears. Besides, it was noted that the addition of seed layer boost the growth on a (002) direction. The experimental values of the Raman frequencies allowed in backscattering measurements and their lines widths confirm the high crystalline quality of the Wurtzite AlN.

Our research results shows that the texture of the elaborated AlN thin films is influenced by the use of the semi conductor seed layer surface.