Study Of AlN Thin Films Deposited By Pulsed Laser Deposition

Aluminum nitride (A1N) films were prepared on p-Si (100) substrates by pulsed laser deposition (PLD). By optimizing the experimental parameters, A1N films with high quality were obtained. Annealing treatments were performed on a part of samples. The structural properties of A1N films such as crystallinity, composition and surface morphology were studied by x-ray diffraction (XRD), Fourier transform infrared Spectroscopy (FTIR) and scanning electron microscopy (SEM). Efforts were made to investigate the influences of such factors as substrate temperature, nitrogen (N2) pressure, laser energy density, pulsed repetition and annealing on structural properties of A1N films. The main results are shown below.(1) Highly oriented A1N (100) films were successfully fabricated at room temperature under different N₂ pressure on p-Si (100) substrates by PLD. Along with the increasing of N₂ pressure, the intensity of A1N XRD peak becomes notably better; the FTIR peak becomes more prominent, which indicate that the samples comprise purer A1N phase and the combination of Al-N bonds is strengthened. But a number of farraginous particles appear on the surfaces of the samples and the films become rougher.(2) The diffused length of atoms on growth surface increase because of the high substrate temperature, which improves the crystallization process. But the high temperature also causes serious loss of N. The introduction of N₂ effectively compensates the loss of N. The energy of particles reduces and the collision between particles becomes more acutely when the N₂ pressure arises, the surfaces of A1N films become rougher. (3) The crystallinity of AIN films can be enhanced by increasing the laser energy density, but the surface of the samples becomes rougher. Annealing treatment can improve the crystal quality of the films, but destroy the smoothness of the surface. Pulse repetition affects little to the growth of AIN films.