Preparation of highly c-axis oriented AlN films on Si substrate with ZnO buffer layer by the DC magnetron sputtering

Highly c-axis oriented AlN thin film was manufactured on Si (111) substrate using ZnO buffer layer by the direct current (DC) magnetron sputtering method. The X-ray diffraction results showed that the AlN/ZnO thin films had a perfect c-axis preferred orientation, and the full width at half maximum (FWHM) of the rocking curves of the (002) AlN peak decreased remarkably. Atomic force microscopy displayed that the AlN films with ZnO buffer layer had a dense, uniform and crack-free uniform microstructure compared to the microstructure of the AlN films grown on Si substrate. The average grain size and RMS surface roughness of the ZnO layers were, respectively, 90 nm and 3.4 nm. The scanning electron microscopy images showed that the AlN/ZnO thin films presented an obvious and quite uniform columnar structure, which are well aligned to the surface normal direction. The current–voltage curves results indicated that the ZnO buffer layer highly improved the insulating properties of the AlN films.

► Highly c-axis oriented AlN films were grown on Si substrate using ZnO buffer layer. ► The AlN films with ZnO buffer layer showed a small FWHM and RMS surface roughness. ► The AlN/ZnO thin films presented an obvious and quite uniform columnar structure. ► The electrical properties of AlN/ZnO films were studied upon I–V curves. ► The ZnO buffer layer highly improved the insulating properties of the AlN films.