Structural and morphological evolution of aluminum nitride thin films: Influence of additional energy to the sputtering process

• c-axis oriented AlN thin films were grown on silicon by RF magnetron sputtering
• The influence of sputtering parameters on structure and morphology was investigated
• The competition between nucleation rate and mobility determines physical properties

Aluminum nitride (AlN) thin films were deposited on SiO2/Si substrates by radiofrequency (RF) magnetron sputtering using an aluminum target. The influence of the deposition parameters – such as nitrogen concentration in the sputtering atmosphere, RF power, total working pressure and substrate bias voltage – on the structure, morphology and composition of the thin films was discussed. The structure was studied using X-ray diffraction (XRD), the morphology was studied using scanning electron microscopy (SEM) and the composition was studied using energy dispersive spectroscopy (EDS). These investigations showed that all of the films grew preferentially along the c-axis regardless of the deposition conditions, without the application of external heating, whereas the grain size and morphology strongly depended on the process parameters. Additional energy, which was supplied to the growing films by increasing the power or decreasing the working pressure, improved the crystallinity, but compressive stress was induced in the samples, thus resulting in a surface morphology evolution.

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