Abstract: Using Ga₂O₃ as Ga source, the GaN films are successfully deposited on Si (111) substrates by two-step method of sol-gel and high nitridation temperature technique. The as-prepared films were confirmed as single crystalline GaN with wurtzite structure by X-ray diffraction (XRD). The dimension of GaN crystal particulates is smaller than 100nm under the observation of scanning electron microscope (SEM). Moreover, E1 (TO) vibrational mode of GaN are surveyed in IR spectrum of the GaN films. Vibrational frequency of GaN small clusters is calculated using density functional theory (DFT). The results show that the vibrational frequencies of the Ga reached clusters are close to the peaks of the phonon vibration modes of the wurtzite structure GaN, and 2200cm^-1 is an intensive vibrational frequency of N--N bond stretch in N reached GaN. FTIR of the sample are analyzed in further.

Key words: GaN film, sol-gel, density functional theory(DFT)