Plasma-assisted hot filament chemical vapor deposition of AlN thin films on ZnO buffer layer: toward highly c-axis-oriented, uniform, insulative films

c-Axis-oriented aluminum nitride (AlN) thin film with improved quality was deposited on Si(111) substrate using ZnO buffer layer by plasma-assisted hot filament chemical vapor deposition. The optical and electrical properties and surface morphology as well as elemental composition of the AlN films deposited with and without ZnO buffer layer were investigated using a host of measurement techniques: X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, field emission scanning electron microscopy (FESEM), and current-voltage (I-V) characteristic measurement. The XRD and XPS results reveal that the AlN/ZnO/Si films are free of metallic Al particles. Also, cross-sectional FESEM observations suggest formation of a well-aligned, uniform, continuous, and highly (002) oriented structure for a bi-layered AlN film when Si(111) is covered with ZnO buffer. Moreover, a decrease in full width at half maximum of the E-2 (high)-mode peak in Raman spectrum indicates a better crystallinity for the AlN films formed on ZnO/Si substrate. Finally, I-V curves obtained indicate that the electrical behavior of the AlN thin films switches from conductive to insulative when film is grown on a ZnO-buffered Si substrate.