Study On Different Preferred Orientation AlN Films Prepared By Pulsed Laser Deposition

AlN thin film is extensively applied in acoustic surface wave devices, microelectronics and optical devices due to its stable physical and chemical properties, high mechanical strength, sound insulation, wide direct band gap, high thermal conductivity, low thermal expansion coefficient, etc. Preparation of AlN film has aroused widespread concern and interest.Firstly, in this paper AlN thin films with different preferred orientation were prepared by pulsed laser deposition by optimizing the laser energy, growth temperature, environmental bias conditions. X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy and other equipment was used to detect the crystallization, surface morphology and other structural features of samples. The results showed that when the laser energy is 600mJ/puls, AlN thin films have the best crystallinity and preferred orientation of the surface. They also have the best performance for the isotropic plane, not the epitaxial growth.Secondly, select the laser energy 600mJ/puls, change the substrate temperature, the results show that when the temperature is at 600℃, AlN films are (110) preferred orientation direction; when the temperature is less than 400℃,, AlN film is no longer (110) direction preferred orientation, but (002) preferred orientation direction, when the substrate temperature is 250℃, (002) preferred orientation direction of AlN thin films is the strongest, AlN thin films with (002) preferred orientation direction on quartz and sapphire substrates also can be grown under the same conditions.Last, AlN thin films were prepared with different environmental bias, the results show that when the bias of the N2 pressure is higher than 2×10-4Pa AlN film can't crystalize. Only under high vacuum conditions AlN films with preferential orientation can be prepared. This paper discussed and studied AlN films with different preferred orientation. The study showed that most important conditions for AlN film by PLD is as follows: the kinetic energy of AlN determines the size of crystallinity and preferred orientation , when the kinetic energy is greater, the crystallinity is the higher. the smalle kinetic energy is not conducive to the crystallization. Through study in the paper, AlN thin films with (110) and (002) preferred orientation can be prepared and provided a strong guanrantee for the further application.