Pulsed laser deposition of AlN thin films

Aluminum nitride (c-AlN) thin films were deposited at room temperature on silicon substrates by nitrogen-ion-assisted pulsed laser ablation of a hexagonal AlN target. A KrF excimer laser with pulse duration of 23 ns and wavelength of 248 nm was used as a laser source for the ablation. A nitrogen ion beam with energy in the range from 200 to 800 eV is used to co-process the deposition. With this technology, it's possible to independently control the energy of the AlN radicals in the ablated plasma and the nitrogen ions in the ion beam to improve the quality of the deposited thin films. Moreover, the nitrogen ion implantation can also compensate the loss of nitrogen species in the ablation process. X-ray diffraction (XRD), Raman spectrum and X-ray photoelectron spectroscopy (XPS) were used to characterize the deposited thin films. The deposited thin films exhibit good crystal properties with sharp XRD peaks. The influences of the nitrogen ion beam energy on the electronic and structural properties of the deposited thin films were studied. The nitrogen ions can effectively promote the formation of stable Al-N bonds and improve the crystal properties of the deposited thin films. A nitrogen ion energy of 400 eV is proposed.