Irradiation with phosphorus ions modifies the structure and tunable band-gap of a hexagonal AlN thin film

Aluminum nitride (AlN) thin films were prepared via Metal organic chemical vapor deposition (MOCVD). The as-grown films were implanted by constant 700 keV energy and swift P ions of influences in different ranges from 1 x 10(13), 1 x 10(14) to 5 x 10(14) ionscm(-2) with the help of ion beam analysis. The intensity of the thin film decreases with increasing ion fluence, and a decrease in crystallinity takes place at higher ions fluence 5 x 10(14) ionscm(-2). The presence of impurities has been stated to be directly related to the crystalline properties of the samples. Lattice amorphization is observed for the sample irradiated with a fluence of 5 x 10(14) ionscm(-2), which is also confirmed by X-ray diffraction (XRD) analysis. Rutherford backscattering spectroscopy (RBS) was used to determine the composition and thickness of the thin films. The irradiation has evolved changes in the microstructure and optical properties with changes in the band-gap of the samples. We report a tunable band-gap with increasing in P ion doses and suggest that the modifications in structural and optical properties of thin films can be controlled by optimizing the implantation conditions. The latter results illustrate one of the most significant advantages of thin film surface acoustic waves (SAW) technology, namely one can exploit both the piezoelectric properties of the film and the acoustic properties of the substrate and hence devise components with superior performance.